<PAGE>

                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM 10-K

[X]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
     SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended  December 31, 2000

[_]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
     SECURITIES EXCHANGE ACT OF 1934

For the transition period from __________ to  __________

Commission file Number: 0-22756
                                  ATMI, Inc.
                                  ---------
            (Exact name of registrant as specified in its charter)


               Delaware                                  06-1481060
               --------                                  ----------
  (State or other jurisdiction of           (I.R.S. Employer Identification No.)
  incorporation or organization)

      7 Commerce Drive, Danbury, CT                        06810
      -----------------------------                        -----
 (Address of principal executive offices)               (Zip Code)

                                 203-794-1100
                                 ------------
             (Registrant's telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

                                             Name of each exchange
         Title of each class                 on which registered
         -------------------                 -------------------
               None                            Not Applicable

Securities registered pursuant to Section 12(g) of the Act:

                         Common Stock, $.01 par value
                         ----------------------------
                             (Title of each class)

------------------------------------------------------------------
Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. Yes  x  No __
                                        -

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, and will not be contained, to the
best of registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K [_]

The aggregate market value of the voting stock held by non-affiliates of the
registrant at March 21, 2001, was approximately $496,175,000 based on the
closing price of $16.6875 per share.

The number of shares outstanding of the registrant's common stock as of March
21, 2001 was 30,248,000.

DOCUMENTS INCORPORATED BY REFERENCE:

 Proxy Statement for the Annual Meeting of Stockholders to be held on May 23,
                               2001 (Part III).
<PAGE>

                                  ATMI, INC.
                          Annual Report on Form 10-K
                  For the Fiscal Year Ended December 31, 2000

                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
Part I                                                                                                Page
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<S>                                                                                                  <C>
Item 1.         Business...........................................................................    3

Item 2.         Properties.........................................................................   15

Item 3.         Legal Proceedings..................................................................   15

Item 4.         Submission of Matters to a Vote of Security Holders................................   16

Item 4A.        Executive Officers of the Registrant...............................................   16

Part II
-------

Item 5.         Market for Registrant's Common Equity and Related
                Stockholder Matters................................................................   17

Item 6.         Selected Financial Data............................................................   18

Item 7.         Management's Discussion and Analysis of Financial
                Condition and Results of Operations................................................   19

Item 7A.        Quantitative and Qualitative Disclosures About Market Risk.........................   24

Item 8.         Financial Statements and Supplementary Data........................................   24

Item 9.         Changes In and Disagreements with Accountants on
                Accounting and Financial Disclosure................................................   24

Part III
--------

Item 10.        Directors and Executive Officers of the Registrant.................................   24

Item 11.        Executive Compensation.............................................................   24

Item 12.        Security Ownership of Certain Beneficial Owners and Management.....................   24

Item 13.        Certain Relationships and Related Transactions.....................................   24

Part IV
-------

Item 14.        Exhibits, Financial Statement Schedule, and Reports
                on Form 8-K........................................................................   25

Signatures      ...................................................................................   27

Index to Consolidated Financial Statements and Financial Statement Schedule........................  F-1
</TABLE>
<PAGE>

                                    PART I

Item 1.   Business.

     ATMI is a leading supplier of materials, equipment and related services
used worldwide in the manufacture of semiconductor devices. ATMI specifically
targets the "front-end" semiconductor materials market. This market includes the
processes used to convert a bare silicon wafer into a fully functional wafer
that contains many copies of a semiconductor device or "chip". To complete the
manufacturing process, this functional wafer is taken through a "back-end"
manufacturing process that includes wafer dicing into chips, packaging and
testing. ATMI's customers include most of the leading semiconductor
manufacturers in the world.

     ATMI has further refined its market focus to target only specialty
materials used in front-end semiconductor manufacturing. These specialty
materials are used in eight key process steps that are used repetitively to add
functionality to a silicon wafer. In recent years, the semiconductor industry
has grown worldwide and front-end manufacturing processes have become
increasingly complex, resulting in rapidly changing requirements for
semiconductor materials. ATMI has capitalized on the growth of the semiconductor
industry in general, and front-end processing in particular, through:

     .    a comprehensive research and development program that has provided a
          stream of proprietary and patented products for this market;

     .    a strategy of delivering a complete materials solution to our
          customers including materials, packaging, delivery systems, sensing
          and abatement; and

     .    an aggressive mergers and acquisitions effort that has allowed us to
          more rapidly move towards one-stop purchasing for our customers.

ATMI has organized its operations along two business segments: Materials and
Technologies.

Materials provides:

     .    a broad range of ultrahigh-purity semiconductor materials; and

     .    semiconductor materials packaging and delivery systems.

Technologies provides:

     .    sensors for the workplace and environment that detect materials as
          they move through the workplace;

     .    point-of-use environmental equipment that abates materials;

     .    specialty thin film deposition services that provide coated wafers
          directly to our customers; and

     .    outsourced parts cleaning and semiconductor fabrication tool
          maintenance.

ATMI also conducts its venture activities and its government-funded research and
development activities through Technologies.

     ATMI's business has evolved to consist of a mix of consumables and services
that track wafer starts, or the number of silicon wafers processed into fully
functional semiconductor devices, and equipment purchases, which generally track
the expansion of industry capacity. Consequently, the Company believes that its
overall business is less volatile than that of a typical semiconductor capital
equipment supplier. Materials and Technologies accounted for approximately 46%
and 54%, respectively, of ATMI's revenues in 2000, and approximately 48% and
52%, and 42% and 58% respectively, of its revenues in 1999 and 1998.

     Over the last five years, ATMI has achieved a leadership position by
providing a more complete line of products than its competitors through
innovation and acquisitions. The Company plans to continue its growth through
product line expansion in each of its existing market segments and to leverage
its core technology to create new high growth businesses. Additionally, we
expect to leverage our various product offerings that surround the various
process tools in a semiconductor fab into a service proposition where ATMI can
manage the lifecycle of material flow through a customer's manufacturing
process, from delivery to abatement.

                                       3
<PAGE>

     On February 7, 2001, in response to softening industry conditions and the
Company's intent to more aggressively integrate previous acquisitions and reduce
costs of infrastructure, a restructuring initiative was announced. The Company
will take a pre-tax charge of approximately $9.0 million, which will be
recognized in the first quarter of 2001 to reflect this initiative, comprised of
the following: involuntary employee termination benefits; write-offs due to
asset impairments; and facility exit costs, including early lease termination
fees. This charge is anticipated to be funded with operating cash flows. The
project initiative will be carried out over twelve months and includes certain
facility closures and the related relocation of production assets, a reduction
in workforce in administrative, operational, and sales functions and the
outsourcing of non-core activities, as well as asset impairments related to
those initiatives. These actions are expected to result in a net employment
reduction of approximately 10% of the workforce.

Semiconductor Industry Background

     The semiconductor industry has grown in recent years as the use of
semiconductor devices has proliferated in a wide variety of consumer and
industrial products, especially in computing, networking and communications
equipment. This increase in demand for semiconductor devices has been fueled by
the ability of semiconductor manufacturers to deliver products with:

     .    consistently enhanced performance characteristics and functionality;

     .    improved reliability;

     .    increased memory capacity; and

     .    reduced size, weight, power consumption and cost.

These advances have been made possible by innovations in the fabrication
processes, equipment and the materials used in manufacturing advanced
semiconductor devices. At the same time, as the construction and management of
fabrication facilities has become more complex, semiconductor manufacturers have
sought to streamline their supplier relationships and reduce the number of
suppliers upon which they rely. In turn, this has driven significant
consolidation among the providers of semiconductor capital equipment and
materials and materials delivery systems.

     Semiconductor devices are manufactured by repeating a complex series of
process steps on a wafer substrate, usually made of silicon. The primary process
steps include various kinds of materials deposition (physical vapor deposition,
chemical vapor deposition, electrochemical deposition, ion implant and spin-on),
etch, wafer preparation (chemical mechanical polishing) and patterning
(photolithography).

     During deposition processes, several layers of conducting, semiconducting
or insulating thin films are formed on a wafer. Precise and reliable control of
the deposition of these films is vital to the ultimate performance of an
individual device.

     The most mature processes for thin film deposition and modification are
physical vapor deposition, also known as PVD or sputtering, ion implantation and
spin-on deposition. In PVD, which is used primarily for the deposition of
conducting or metal layers, a high energy beam is directed at a high purity
metal target which in turn causes the displacement of metal atoms that are
showered over the wafer, coating it with a thin metallic film. Ion implantation
is a gas-based process used principally to modify (or dope) semiconducting
layers with a high energy beam of material that is "implanted" into an existing
thin film. In spin-on deposition, a spinning wafer is treated with a solution of
materials and solvent. The solvent is vaporized, leaving the material in place
which is usually further heat treated to form the desired thin film.

     Chemical vapor deposition, or CVD, is a newer process used in the
deposition of semiconducting and insulating thin films. In the CVD process,
wafers are placed in a sophisticated reaction chamber and a specially designed
gas or vaporized liquid material is introduced. Simultaneously, a form of
energy, such as heat or plasma, is added to the reactor to cause the
decomposition of the material being introduced. As a result of this
decomposition, a thin film of material is deposited on the surface of the wafer.
The advantages of CVD over PVD based processes include:

     .    the relative thinness of the films applied to the wafer;

     .    conformality (ability to coat evenly, especially in holes and trenches
          designed into the device);

     .    purity; and

     .    the ability to coat large areas.

These advantages have led to rapid growth in sales of reactors and related CVD
process consumables and equipment. Consumables

                                       4
<PAGE>

and related equipment include the raw materials used in the CVD process and the
delivery systems required to transport the materials around a semiconductor
plant and to a reactor.

     An even more recently developed process called electrochemical deposition,
or ECD, is now growing rapidly as a result of the industry's desire to use
copper as the conducting layer in certain devices. In ECD, the wafer is
submerged in a bath of copper electroplating solution which, when appropriately
charged, deposits a thin film of copper on the wafer.

     Etch is a process that selectively erodes away certain thin film materials.
It is carried out either "dry" with corrosive gases or "wet" with energized
liquids. Chemical mechanical polishing, or CMP, is used to prepare a wafer for
photolithography. As wafers are processed, thin film thicknesses inevitably vary
across the surface of the wafer. Due to the fine line widths used in
photolithography, present day wafers need to be perfectly flat. CMP flattens the
processed wafer by polishing the wafer using a mechanical polishing pad and a
slurry, which is an abrasive solution containing solid materials and chemicals
which selectively erodes away the appropriate excess materials.

     Photolithography is the process whereby patterns are developed on the wafer
surface. The process is begun by spinning a photosensitive material called a
"photoresist" or "resist" onto the wafer surface and shining light through a
patterned photomask to selectively harden the resist. The resist is then
developed by stripping or otherwise removing excess resist material and allowing
for the fabrication of the wafer's circuitry.

Materials and Delivery Systems

     The market for semiconductor thin film materials has expanded with the
growth of the market for semiconductor devices. The design of new thin film
deposition materials and equipment to transport these materials around a
semiconductor plant has experienced ongoing innovation. This innovation has been
driven by the demand for expanding semiconductor device capabilities and
corresponding decreases in circuit dimensions. Safe and effective thin film
deposition requires dedicated systems designed to deliver and vaporize precursor
materials for deposition in reactors without contamination or inadvertent
release of toxic gases.

     Because thin film materials are consumables, the market for these materials
and delivery systems generally tracks wafer starts, as opposed to the market for
equipment, which generally tracks investment in new plants. The thin film
materials market is also segmented into a wide variety of material types and
forms. For example, many thin film precursors are now sold as pressurized gases,
which allows for easy transport around a typical semiconductor manufacturing
plant. However, many of these gases are toxic and/or hazardous, leading to the
development of safer alternatives including the use of liquid or solid materials
and the adoption of gas handling technologies and delivery systems that minimize
the danger of a catastrophic release of toxic gas.

     Materials Packaging. Semiconductor materials have exceptional purity
requirements due to the extremely low tolerances for impurities and particulates
in semiconductor processing. Gases are in a form whereby particulates can be
readily managed. Liquids and solids, however, require special packaging to
minimize exposure to air and particulates.

     Materials Sensing and Monitoring. Semiconductor gases pose unique toxicity
and environmental difficulties. As a result, the need for devices to sense and
warn personnel of leaks or possible catastrophic releases of these gases is
compelling. To that end, a market for toxic gas sensing devices and systems has
grown up in tandem with the semiconductor industry. Semiconductor fabs are now
outfitted with a high level of sensing technology to protect the workplace and
the environment. Furthermore, this technology is being integrated with factory
operations to prevent and/or minimize damage or productivity of the plant and
its personnel.

     Sensors are also required to monitor materials purity and concentration.
The ability to integrate sensors to control processing equipment is also
critical to the productivity of the high capital intensive semiconductor fabs.
So-called "in-process sensing" is growing rapidly with the increasing complexity
of semiconductor processing.

Environmental Equipment

     The use of gas and vapor based processes has led to the development of
environmental equipment designed to abate gaseous effluent. For example, less
than 40% of the materials entering a CVD reactor are deposited as a thin film.
The remainder of the source materials, and certain by-products, constitute an
effluent stream containing toxic and hazardous material that must be abated to
meet increasingly strict worldwide environmental, safety and health regulations.
Traditionally, abatement has been accomplished by the use of "whole plant"
environmental systems, which aggregate the effluents from an entire facility.
However, variations in the processes used and the drive for increased
productivity have led to the growth of point-of-use environmental systems in
which a single environmental unit is attached to a single reactor. This approach
provides for superior abatement because the system can be tuned to the unique
hazards of a particular effluent stream. In addition, point-of-use environmental
systems can improve plant productivity by reducing downtime associated with
servicing environmental systems.

                                       5
<PAGE>

Epitaxial Services

     The demand for higher performance integrated circuits and discrete
semiconductor devices has driven the use of epitaxial wafers in a wide variety
of applications. Epitaxial, or "epi", wafers are wafers on which CVD thin films
have been deposited. A merchant market for epitaxial wafers, primarily silicon
epitaxial wafers, has in recent years developed due to the high degree of
expertise and significant capital expenditures required by epitaxy. This market
is subdivided into "generic" wafers for high volume applications such as dynamic
random access memory, or DRAM, and "specialty" wafers for use in applications
such as automotive electronics and sensors, silicon-based low power
telecommunications circuits, analog power controls and robust application-
specific integrated circuits.

     The continued drive for improved device performance and new applications
for integrated circuits has led to the development and commercialization of
alternative semiconductor technologies. A newer generation of devices has
emerged that uses epitaxial wafers made of III-V and wide bandgap materials, as
opposed to silicon, to achieve this improved performance. III-V semiconductors,
including gallium arsenide and indium phosphide, are finding increasing use in
wireless communication devices where high frequency performance is critical, in
optoelectronic devices where the electronic structure of the III-V
semiconductors allows energy-efficient light generation and in solar cells for
satellite applications where efficient generation of electricity is critical.
Wide bandgap semiconductors, such as silicon carbide and gallium nitride, offer
advantages in high power, optoelectronic and high temperature devices.

Outsourced Parts Cleaning and Tool Maintenance

     With device manufacturers increasing their desire for optimally efficient
manufacturing processes, there is a growing trend for outsourcing services which
are non-essential to the production of devices. Services such as parts cleaning
and tool maintenance, when performed as an outsourced activity, can
significantly increase the up-time of manufacturing equipment and lower the cost
of ownership of these process tools.

ATMI's Strategy

     ATMI's objective is to establish and enhance leadership positions in each
of the market segments it serves. The Company's strategy consists of the
following key elements:

     .    Target high growth, high margin specialty markets that use ATMI's core
          materials technologies and require products that are consumed in the
          production process.

     .    Seek to provide full market-basket solutions, or "one-stop shopping",
          through innovation and acquisitions in each of ATMI's target markets
          to help its customers streamline supplier relationships.

     .    Provide added value through advanced packaging and dispensing systems
          designed to meet the demands of users for greater levels of purity,
          productivity, safety and environmental responsiveness.

     .    Leverage ATMI's technology leadership by investing extensively in
          developing proprietary and patented materials and materials handling
          technology which the Company uses to commercialize new products to
          meet customer requirements.

     .    Form strategic alliances, including joint development programs and
          collaborative marketing efforts, to accelerate the introduction of
          ATMI's products into markets that have manufacturing and/or
          distribution barriers.

Businesses and Products

     ATMI conducts its operations through two primary business segments:
Materials and Technologies.

                                       6
<PAGE>

Materials

     ATMI believes Materials is one of the fastest growing suppliers of
ultrahigh purity semiconductor materials and related packaging and delivery
systems to the semiconductor industry. The Company has taken advantage of the
changes in the market for materials and delivery systems by:

     .    developing and commercializing a wide range of "front-end"
          semiconductor materials;

     .    commercializing innovative bulk delivery systems which automatically
          deliver materials of the highest purity and consistency to a process;

     .    developing innovative packaging systems that allow for the
          introduction of low volatility liquids and solids to semiconductor
          processes;

     .    developing and commercializing patented low-pressure gas delivery
          systems for safe handling and delivery of toxic and hazardous gases to
          semiconductor process equipment; and

     .    developing manufacturing processes to meet the critical purity and
          integrity requirements of the microelectronics industry.

     In meeting the needs of its customers, which include semiconductor device
manufacturers, chemical suppliers and OEMs located throughout the world, and
anticipating their future requirements, ATMI seeks:

     .    to offer the most complete line of consumable and delivery and
          packaging system products;

     .    to offer the most consistent, highest purity materials available;

     .    to offer the most reliable, innovative equipment products;

     .    to improve the level of customer service, technical support and
          response offered and to remain cost-effective to ATMI's customers;

     .    to meet customer needs for statistical quality and process control and
          dock-to-stock programs; and

     .    to continue to meet the industry's needs for advanced materials
          required for future generation devices.

     Products and Services. Materials has four primary product lines, which
consist of liquid materials, liquid delivery systems, gas delivery systems and
advanced packaging and dispensing systems. Materials also provides services
relating to each of these product lines.

     Liquid Materials. ATMI produces a broad range of materials that are used in
making semiconductor devices. In addition to the widely used CVD precursors such
as TEOS and related dopants, ATMI also sells thin film materials used in other
semiconductor manufacturing processes, including phosphorous and boron halides
used for doping by diffusion processing. ATMI also manufactures and sells source
reagents that allow CVD of advanced materials, including titanium nitride,
platinum, copper, tantalum oxide, lead zirconate titanate, strontium bismuth
tantalate and barium strontium titanate thin films. In addition, ATMI has
introduced products for the emerging low-k applications for semiconductor
manufacturing.

     All of these thin films must be of very high purity in order to function
properly within the device, particularly with respect to unwanted metallic
contamination. ATMI believes its cleaning and container technology produces the
most consistent, highest purity chemicals in the industry and ensures their
quality as delivered into the reactor.

     ATMI also produces a wide range of liquid products for photoresist
stripping, edge bead removal, developing and cleaning. In addition, ATMI
provides products serving the rapidly growing market for CMP slurries. ATMI now
provides high performance oxide polishing slurries and expects to introduce
advanced metal slurries.

     Liquid Delivery Systems. ATMI designs, manufactures and sells proprietary
continuous refill and delivery systems. These systems are designed to deliver
ultrahigh-purity thin film materials to the CVD reactors under the desired
physical conditions. ATMI's delivery systems include stainless steel ampules,
stainless steel MINIBULK canisters, stainless steel SKINNIBULK canisters, quartz
bubblers, bulk chemical delivery cabinets, level sensing systems, manual and
continuous refill systems and other application-specific equipment.

                                       7
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     ATMI believes that its continuous refill systems enhance the performance of
the process tools they support by eliminating process downtime resulting from
canister changes. Typically, process tools must cease operation when canister
changes are made to replenish source material. ATMI's bulk refill systems allow
continuous delivery of source material. In addition to the elimination of the
downtime associated with canister changes, this configuration also minimizes the
atmospheric and moisture contamination that can occur during these change-outs.

     Gas Delivery Systems (the SDS or Safe Delivery System). ATMI's patented SDS
product line uses a standard gas cylinder containing an adsorbent material. The
cylinder is filled with gas under conditions such that the gas is adsorbed onto
the material, and the SDS cylinder is at sub-atmospheric pressure, minimizing
any potential leak of hazardous gas and allowing more gas to be introduced into
the cylinder than would be possible under traditional high pressure conditions.
Consequently, material delivery via SDS is safer and provides significantly
higher rates of productivity than traditional methods. Since most semiconductor
processes operate at reduced pressure and the gas can be desorbed or released
from the SDS under vacuum, it can be installed and operated like a conventional
high-pressure gas cylinder. These advantages have led major chip manufacturers
to adopt this technology.

     To date, ATMI has introduced products using the SDS technology to deliver
several gases, including arsine, phosphine, boron trifluoride, silicon
tetrafluoride and germanium tetrafluoride. Each is used to "dope" silicon wafers
using ion implant processes. All of these SDS products are available in
different size cylinders, and some have different adsorbents that allow for
additional gas capacity within a cylinder. These products are manufactured by
ATMI, and for ATMI by Matheson Gas Products, the Company's exclusive distributor
for SDS used in ion implant applications.

     ATMI also believes that significant markets for SDS exist outside ion
implant. The Company has undertaken extensive development efforts to identify
new markets and products for the SDS and related technologies. ATMI believes its
closely related sub-atmospheric gas enhanced ("SAGE") delivery technology will
be applicable to an increasing number of gas delivery applications within the
semiconductor industry. ATMI has commercialized SAGE for high density plasma CVD
applications. Another new product used for managing the SAGE delivery technology
is the RPM delivery system, which provides complete gas management with
pre-programmed automated functions that allow for repeatable performance and
reduces the potential for operator error. Built-in gas detection monitoring
provides fail-safe operational safety. Another related technology, ATMI's
VAC(TM) ("vacuum accuated cylinder") is an ideal gas source for corrosive and
flammable hydrides used in ion implant processes. Although it stores gas at high
pressure, VAC(TM) sources provide significantly improved safety over traditional
high-pressure sources by dispensing gas at only sub-atmospheric pressure.

     Advanced Packaging and Delivery Systems. ATMI manufactures three different
types of NOWPak container assemblies: "Bag-in-a-Bottle"; "Bag-in-a-Can"; and
"Bag-in-a-Drum". Each features a pre-cleaned collapsible inner liner, or "bag",
inside a rugged, high-density polyethylene or stainless steel overpack. The
standard liner film is made of polytetrafluoroethylene which allows virtually
all chemicals to be delivered to the manufacturing process in an unaltered
state. The empty inner liner is easily removed for waste consolidation, and the
outer shell is recyclable or returnable for insertion of a new replacement
liner.

     The largest market for NOWPak's packaging is materials for photoresists.
These materials are typically packaged in one liter through ten liter Bag-in-a-
Bottle containers. The NOWPak's market applications for photoresists used in the
manufacture of active matrix flat panel displays as well as for the
pharmaceutical, biotech and laboratory markets are typically in 18-20 liter Bag-
in-a-Bottle and Bag-in-a-Can containers. Additionally, applications have
recently expanded beyond photolithography chemicals in the semiconductor niche
to include ancillary chemicals, CMP slurries and process chemicals for which the
new 200 liter Bag-in-a-Drum is well suited.

     ATMI also produces packages for high purity solids under the Newform brand
name. The Company makes high-purity flexible Ultra Clean packaging for the
semiconductor and pharmaceutical industries. With its Newform products, ATMI
packages critical solids-sputter targets, wafer and disc shippers, cleanroom
parts and container overwraps. With the NOWPak liquid packaging system and
Newform solids packaging, ATMI is addressing facets of critical packaging for
the microelectronics market.

Technologies

     ATMI has taken advantage of its expertise in semiconductor materials
technology to build a comprehensive product portfolio around this core
technology. Effectively, Materials' business ends with the delivery of a
specialty material to a semiconductor industry process tool. Through its common
core technical understanding of these materials, Technologies delivers products
and services that allow its customers to manage materials flow through the
remainder of the semiconductor factory as well as manage the efficiency of their
process tool. Technologies addresses its customers' needs by providing:

     .    sensing products that protect both the workplace and the environment;

     .    monitoring products for certain processes that ensure the quality of
          the thin film product being produced;

                                       8
<PAGE>

     .    a full range of abatement products that remove potential environmental
          threats from the process exhaust stream;

     .    specialty thin film deposition services for those customers who do not
          desire to perform this operation within their own facilities; and

     .    parts cleaning and tool maintenance services to ensure cost effective
          operation of the customer's process tools.

ATMI believes Technologies is the leading supplier of sensing products,
point-of-use abatement systems, specialty epitaxial deposition services and
parts cleaning and maintenance services to the worldwide semiconductor industry.
Technologies also manages ATMI's ventures portfolio, which includes the Emosyn
smart card device product line and ATMI's optoelectronic materials activities,
until these ventures mature to market critical mass.

     Products and Services. Technologies includes three primary product lines
and services, which consist of sensing products, point-of-use semiconductor
environmental equipment and deposition services.

     Sensing Products. ATMI provides life safety systems to the semiconductor
industry. Because the gases used in semiconductor manufacturing are so toxic,
manufacturers must install systems that protect employees from accidental
releases. ATMI believes that it is now the only company offering a range of
technologies capable of detecting the gases used in semiconductor manufacturing.
Combined with its worldwide systems integration capabilities, ATMI is able to
provide customers with a single contact for the design, installation,
commissioning and sustaining service on complete life safety systems.

     Satellite series electrochemical sensors provide distributed sensors
located at each point requiring gas detection. Electrochemical sensors provide
cost effective and reliable detection of most gases used in semiconductor
fabrication. This sensor's self-check feature and auto-calibration feature
provide maximum reliability and ease of use and are the leading sensor
technology for acid gases in a fab.

     ACM Air Composition Monitors allow the fab to determine the exact
composition of any gas that is emitted in the fab. This system allows the fab to
determine exactly the composition of unknown odors that fab personnel may
detect. It also is the only known detection device in the industry that can
measure NF3 without the need to decompose it into another species for detection.

     TGM Toxic Gas Monitors use molecular emissions spectroscopy to measure and
speciate toxic gases. This system is the leading technology for sensing the very
toxic hydride gases used to dope semiconductor films.

     H2M Hydrogen Monitors use a patented acoustical technology that measures
the time of flight of hydrogen in an enclosed tube. ATMI believes this system is
the only system on the market that can detect hydrogen without interference from
other gases such as hydrocarbons. As a result, ATMI believes this system is the
most reliable way to detect hydrogen.

     Semi-Chem Fluid Process Monitors are unique liquid sensing devices that use
multiple liquid analysis technologies. These devices analyze the signals they
receive with complex algorithms and measure the precise assay of materials that
affect the overall yield of a device.

     ATMI also provides a unique and high value added liquid chemical analysis
and control tool. ATMI believes that it is a market leader in the analysis and
control of the active ingredients in CMP slurries. In addition, ATMI believes
that it is well-positioned to provide leading technology to the semiconductor
copper plating market through product development activities with industry
leaders.

     Point-of-Use Semiconductor Environmental Equipment. ATMI believes it is the
only provider of point-of-use environmental equipment offering all of the key
technologies for effluent gas abatement to the semiconductor industry: dry
chemical; liquid; and active oxidation. As a result of this broad product line,
ATMI believes it is a global market leader in the manufacture and sale of point-
of-use semiconductor effluent abatement equipment. The Company's strategy is to
grow its market share through the continued development and acquisition of new
semiconductor environmental products and services. ATMI believes that this full
line of semiconductor environmental products, coupled with a comprehensive
service and sensing strategy, will allow for continued market penetration by
this business.

     ATMI has four primary environmental equipment product lines. Each of the
four major point-of-use products has cost of ownership advantages for
semiconductor customers in certain applications such as CVD, ion implant and
etch.

                                       9
<PAGE>

     Vector wet scrubbers are designed for cost effective removal of acidic and
high particulate bearing gases commonly used in the wafer fabrication process.
Vector scrubbers recirculate scrubbing water, minimizing overall water use, and
are effective in removing high particulate effluent and, with its optional air-
oxidation inlet, pyrophoric gases. The Vector scrubber is typically used in CVD
and etch applications. It is the leading treatment system for multi-wafer
chamber CVD tools.

     Delatech CDO oxidation and water treatment scrubbers use a combination of
thermal oxidation and wet scrubbing to treat solid particulate and acid gas
applications in a single unit. This system can also be used to treat PFCs
(perfluorinated compounds) believed to be responsible for global warming. This
system is the industry's leading treatment solution for single wafer chamber CVD
tools.

     Novapure dry chemical scrubbers adsorb and concentrate hazardous effluent
through the use of consumable resins at rates many times that of conventional
effluent treatment methods. ATMI believes that, through its patented adsorption
materials, the Company is a market leader for point-of-use semiconductor
effluent dry scrubbing throughout the world. This technology is typically used
for ion implant applications, in conjunction with the SDS product line. It is
also used for etch and certain CVD applications.

     Guardian active oxidation scrubbers treat a variety of combustible
materials used in semiconductor processing. The Guardian product line is
designed for high reliability and very high flow rates of combustible gases
typically used in CVD and flat panel display applications.

     Deposition Services. In addition to deposition on patterned wafers, CVD
thin film processes are used to prepare bare wafers prior to the fabrication of
integrated circuits to provide the wafer surfaces with the desired uniformity of
electrical and physical properties. Such CVD thin film deposition is referred to
as epitaxial deposition, and these wafers when processed are referred to as
epitaxial, or "epi", wafers. The complexity, sensitivity, and capital intensive
nature of the CVD processes used for epitaxy have created a market for epitaxial
thin film deposition services, or contract manufacture of epi wafers using CVD
processes.

     Technologies operates a service business providing specialty epitaxial
deposition services for silicon, III-V and wide bandgap wafers. Desired
electrical and physical properties of the epitaxial layers are specified by the
customer and developed in collaboration with ATMI. The properties of the
epitaxial layers are selected to maximize the performance of the customer's
integrated circuit or device while maximizing yield and minimizing cost. Our
fundamental competitive advantages include the manufacture of high quality
epitaxial layers with high yield. In addition, ATMI differentiates itself by
offering quality epitaxial deposition services with fast turnaround and in
flexible volumes.

     ATMI believes that it is the only provider offering CVD thin film
deposition services for each of the key materials used in semiconductor devices
today, and that the Company is now a world leader in specialty epitaxial
deposition services. ATMI's strategy is to maximize market share through the
continued development and acquisition of new semiconductor thin film products
and services. A key element of the business strategy is to work with the
customer in the early stages of product development to ensure that proven
epitaxial processes are in place when the decision is made to expand into
manufacturing.

     ATMI provides commercial epitaxial deposition services for silicon and
III-V materials. III-V epitaxial wafers are finding increasing use in wireless
communications, satellites and optoelectronics for data and telecommunication
markets. Epitaxial services for wide bandgap semiconductors and several new
products in silicon and gallium arsenide are in development. ATMI is currently
engaged in several collaborations to develop wide bandgap epitaxial wafers for
future optoelectronic, sensor and power device products. Furthermore, ATMI is
developing a silicon germanium epitaxial process for use in silicon-based
heterojunction devices for high speed communication and computation integrated
circuits and a ultrathin silicon on sapphire process for use in high frequency,
low power applications. The Company is also continuing development of epitaxial
structures for gallium arsenide-based electronics devices including
heterojunction bipolar transistors and high electron mobility transistors in
collaboration with ATMI's customers.

     Fab Services. ATMI, through a July 2000 acquisition, has begun the
outsourcing of process tool parts cleaning and refurbishing for the
semiconductor industry. Through a developed expertise in proprietary wet and dry
chemical process cleaning, ATMI takes delivery of various process tool parts and
cleans them for reuse in semiconductor manufacturing, thereby significantly
reducing the spare parts cost for the customer and reducing the cost of running
certain manufacturing processes. As part of this service, ATMI will coordinate
and manage schedules with the fab, change out parts, take parts to offsite
facilities, clean and refurbish the parts, and bring the parts back to the fab.
The focus is currently on implant, diffusion and etch tools, and abatement
tools.

     Ventures. ATMI maintains an active in-house venture program. The primary
goal of this program is to develop next-generation semiconductor materials
technology that is beyond the product development scope of the Company's
existing core businesses. The research and development funding that ATMI applies
to this program is enhanced through federal government contract or partner
funding in nearly all cases.

                                      10
<PAGE>

     Smart Card Device Venture. ATMI, through its Emosyn division, is currently
developing and commercializing integrated circuits for use in smart cards. Smart
cards are credit card-like devices that operate through a chip on the card as
opposed to the more familiar magnetic strip. The smart card is read through
insertion into a "reader" which clamps down on the device and simultaneously
powers it up and performs a multitude of operations. The smart card market is
growing rapidly, especially in Europe, in the mobile phone, health care and
transportation industries. Long term, the Company expects that smart cards will
see wide use in secure internet transactions.

     ATMI entered this market to leverage certain proprietary advanced non-
volatile materials technology. To facilitate the development of these integrated
circuits, ATMI entered into a strategic alliance with a subsidiary of SMH
Swatch, the largest watch maker in Switzerland, to design, develop, manufacture
and distribute these products. In November 1998, ATMI also entered into a
strategic alliance with Xicor, Inc. which gives the Company the right to become
Xicor's exclusive sales channel for Xicor integrated circuit products targeting
smart card applications. ATMI also holds an option to purchase this product line
beginning in 2001.

     ATMI's first smart card products are targeted at the fast-growing markets
for wireless telecommunication subscriber identification module (SIM) cards and
micro-controller-based smart card IC's. The combination of ATMI's expertise in
non-volatile memory technology with SMH Swatch's expertise in ultra-low power
and radio frequency technology has enabled the launch of a device called
"Theseus" which provides high density, speed, power and memory partitioning. The
Company's approach to memory technology design provides a smart card solution
that significantly reduces the major problem of time-to-market for the card
manufacturers with no increase in device size. ATMI shipped its first commercial
product in 1999 and has seen increasing acceptance of its IC products in the
market throughout 2000. At the end of the first quarter 2001, the strategic
alliance with SWATCH came to an end. Both parties have agreed to transition
market support of existing products and independently develop next generation
products and markets.

     Other Venture Activities - Optomaterials. ATMI has oriented much of its
effort in the ventures program area towards the development of optoelectronic
materials, especially gallium nitride. ATMI believes that its unique technology
in this area, in both substrate and epi layer manufacture, will allow it to
enter new rapidly growing markets as either a supplier of these materials or as
a partner in the development of advanced optoelectronic devices such as blue
laser diodes and high performance light emitting diodes.

Customers, Sales and Marketing

     ATMI sells and distributes its products worldwide, both directly and
through manufacturers' representatives. Many of ATMI's customers have
relationships with more than one of ATMI's segments or are acting as
collaborators on ATMI's development programs.

     ATMI distributes its materials and delivery system products to end-use
customers, chemical suppliers and equipment suppliers through its direct sales
force in North America, Europe, Taiwan, Korea and Singapore, complemented by
regional manufacturing representatives in certain parts of Asia. Additionally,
ATMI's equipment product lines are marketed and sold to semiconductor equipment
OEMs, who in turn resell to end users. NOWPak containers are generally sold to
chemical suppliers. The chemical companies then sell their high purity chemicals
in NOWPak containers at the request of end-users. Newform packaging products
have historically been sold directly to semiconductor and pharmaceutical
companies, predominately in Europe. ATMI sells its SDS product into the ion
implant market through an exclusive distribution agreement with Matheson Gas
Products.

     The businesses within Technologies distribute products both directly and
through various manufacturing representatives.

     ATMI distributes its point-of-use environmental equipment and life safety
monitoring equipment through manufacturers' representatives throughout the
world. Direct sales personnel serve as regional managers who coordinate the
representatives' activity within their respective regions. Additionally, ATMI
markets environmental equipment product lines directly to semiconductor end-user
facility managers to provide full-fab environmental and monitoring solutions, as
well as installation and on-going service.

     ATMI markets and sells its thin film deposition services and epitaxial
wafers primarily on a direct basis. In particular, silicon epi wafers and
services are sold directly throughout the world. Wide bandgap and III-V
epitaxial wafers are sold directly in North America and through distributors and
agents in Europe and Asia.

     Substantially all of ATMI's sales are to customers in the worldwide
semiconductor industry. Results of operations, therefore, are materially
dependent upon economic and business conditions in the semiconductor industry.
The semiconductor industry has historically experienced significant growth;
however, periods of reduced semiconductor unit demand and manufacturing
overcapacity could result in significantly reduced demand for semiconductor
materials, capital equipment and wafer processing services.

                                      11
<PAGE>

Manufacturing

     The following table summarizes the location, products and size of ATMI's
various manufacturing facilities as of December 31, 2000.

<TABLE>
<CAPTION>
----------------------- ---------------------------- -------------------------- -----------------------------
                                 Location                    Products                  Square Footage
                        ---------------------------- -------------------------- -----------------------------
<S>                     <C>                          <C>                        <C>
                        Bloomington, MN              .   chemical containers              70,000
                                                         and dispensing
        Materials                                        systems
                        ---------------------------- -------------------------- -----------------------------
                        Burnet, TX                   .   liquid materials                 30,000
                                                     .   delivery systems
                        ---------------------------- -------------------------- -----------------------------
                        Carrollton, TX               .   liquid materials                 30,000
                        ---------------------------- -------------------------- -----------------------------
                        Milpitas, CA*                .   delivery systems                 12,000
                        ---------------------------- -------------------------- -----------------------------
                        Danbury, CT                  .   liquid materials                 50,000
                        (Corporate Headquarters) -   .   delivery systems
                        See Item 2                   .   SDS
                        ---------------------------- -------------------------- -----------------------------
                        Anseong, South Korea         .   liquid materials                  9,000
                        ---------------------------- -------------------------- -----------------------------
                        Hoegaarden, Belgium          .   packaging products               30,000
----------------------- ---------------------------- -------------------------- -----------------------------
                        Albuquerque, NM              .   fab services                     12,000
                        ---------------------------- -------------------------- -----------------------------
                        Buffalo Grove, IL*           .   monitoring equipment             33,000
                        ---------------------------- -------------------------- -----------------------------
                        Dallas, TX                   .   fab services                     40,000
                        ---------------------------- -------------------------- -----------------------------
                        Danbury, CT                  .   proprietary                      22,000
                        (Corporate                       adsorbents for gas
                        Headquarters) -                  treatment products
       Technologies     See Item 2                   .   wide bandgap
                                                         epitaxial wafers
                                                     .   high performance
                                                         thin films
                        ---------------------------- -------------------------- -----------------------------
                        Mesa, AZ                     .   specialty silicon                33,000
                                                         epitaxial wafers
                        ---------------------------- -------------------------- -----------------------------
                        Napa, CA                     .   point-of-use                     40,000
                                                         environmental
                                                         equipment
                        ---------------------------- -------------------------- -----------------------------
                        Phoenix, AZ                  .   III-V epitaxial                  57,000
                                                         wafers
                                                     .   fab services
                        ---------------------------- -------------------------- -----------------------------
                        Portland, OR                 .   fab services                    12,000
                        ---------------------------- -------------------------- -----------------------------
                        San Jose, CA                 .   point-of-use                     45,000
                                                         environmental
                                                         equipment
                        ---------------------------- -------------------------- -----------------------------
                        Bonn, Germany                .   monitoring equipment             12,000
                        ---------------------------- -------------------------- -----------------------------
                        Liexlip, Ireland             .   fab services                      8,000
                        ---------------------------- -------------------------- -----------------------------
                        Munich, Germany              .   monitoring equipment             30,000
                        ---------------------------- -------------------------- -----------------------------
                        Seoul, South Korea           .   point-of-use                      3,000
                                                         environmental
                                                         equipment
----------------------- ---------------------------- -------------------------- -----------------------------
</TABLE>

     * ATMI will close the Buffalo Grove, IL, and Milpitas, CA, facilities and
will reduce space requirements in certain existing facilities as part of the
restructuring efforts in 2001.

                                      12
<PAGE>

Competition

Materials

     ATMI's primary competitors in semiconductor materials in the United States
are the Schumacher Division of Air Products Corporation, the Diffusion Systems
Division of Arch Chemical (in CVD precursors), the EKC division of ChemFirst
Corporation and the ACT division of Ashland Chemical (in photolithography
ancillaries). ATMI also competes with these companies outside of the United
States as well as with Yamanaka Hutech Corporation and Kojundo in Asia, and
Merck in Europe. There are a number of other smaller participants in these
markets.

     There are currently no direct competitors to ATMI's patented SDS product.
Several companies, however, provide gases in high-pressure containers that
compete with the process capability of SDS. There are numerous domestic and
foreign companies that offer products that compete with ATMI's packaging and
chemical dispensing system products. However, ATMI believes that its ability to
compete in the markets for containers and dispensing systems is dependent
largely upon its patented NOWPak technology and its proven ability to
continually enhance and improve its products and technologies.

Technologies

     ATMI's competitors in effluent abatement include CS GmbH, Ebara, Japan
Pionics, and the Edwards Division of British Oxygen Corporation ("BOC"). The
Company's primary competitors in sensing products include the MDA division of
Zellweger Analytics in the United States and Europe and Riken in Japan.

     ATMI has different competitors in each of its primary deposition services
areas. In silicon epi, ATMI competes with Moore Technologies, Reaction
Technologies and a number of specialty wafer manufacturers with their own epi
capabilities. In some product areas, ATMI competes with the major silicon wafer
manufacturers including Wacker, Mitsubishi Silicon America and Sumitomo. In
III-V epi, ATMI competes with Kopin, IQE, Emcore and a number of other
manufacturers.

     ATMI has various small, localized competitors that provide a variety of
parts cleaning services to semiconductor facilities. Primary competitors include
Kuchina, recently acquired by the Edwards division of BOC, Environclean, a
division of Norton Chemical, and privately-owned Pentagon, Inc.

     ATMI's Emosyn business is evolving as a commercial presence in a very large
smart card IC marketplace. Several large companies are also working to provide
semiconductor devices into that marketplace, including Phillips, Atmel and
Samsung.

Research and Development

     The Company's research and development expenses consist of personnel and
other direct and indirect costs for internally funded project development.
ATMI's external funding is almost exclusively from various agencies of the
federal government. ATMI also participates in joint development efforts with
certain semiconductor manufacturers and semiconductor equipment OEMs. Total sums
expended for research and development for the years ended December 31, 2000,
1999 and 1998 were $31.4 million, $23.1 million and $22.5 million, respectively.
Of those amounts, $3.2 million, $4.7 million and $5.9 million, respectively,
were externally funded and are classified within cost of revenues on the
consolidated financial statements, and $28.2 million, $18.4 million and $16.6
million, respectively, were internally funded expenditures and are classified as
research and development expenses on its consolidated financial statements.
Total research and development expenditures from internal and external funding
represented 10.5%, 11.4% and 13.4% of revenues in 2000, 1999 and 1998,
respectively.

Strategic Alliances

     ATMI forms strategic alliances, including joint development programs and
collaborative marketing efforts, to accelerate the introduction of its products
into markets that have manufacturing and/or distribution barriers. These
programs have led to significant technological advances, including the
development of proprietary advanced materials and semiconductor manufacturing
processes. Most of ATMI's strategic alliances are with leading semiconductor
manufacturers or OEMs, such as Applied Materials, IBM, Lucent Technologies,
Micron Technology, Novellus, Siemens and Texas Instruments, each of which has
participated with the Company in advanced materials and process development
programs. These programs enhance ATMI's core technology base, promote the
introduction of targeted products and reduce ATMI's need to make research and
development and capital expenditures.


                                      13
<PAGE>

Backlog

     Neither our liquid materials business, which conducts significant portions
of its business with open-ended, long-term supply contracts which do not specify
quantities, nor our specialty thin film deposition services business, which
generally operates with fast turnaround, maintain significant backlog. Also, the
SDS gas delivery source product, marketed through Matheson as an exclusive
distributor for the ion implant market, carries no backlog. Because orders
comprising our backlog may be canceled, and delivery schedules may be changed,
our backlog at any particular date may not be indicative of actual sales for any
succeeding period.

     The Company considers orders for products shippable within six months of
the backlog date and fully executed and funded research contract awards as of
the backlog date as firm backlog. As of December 31, 2000, the Company had firm
backlog of approximately $32.3 million, consisting of approximately $30.0
million of product orders and approximately $2.3 million of executed and funded
research contracts. This compares to a firm backlog level of approximately $25.2
million as of December 31, 1999, which consisted of approximately $22.4 million
of product orders and approximately $2.8 million of executed and funded research
contracts.

Patents and Proprietary Rights

     ATMI has made a significant investment in securing intellectual property
protection for its technology and products. ATMI protects its technology by,
among other things, filing patent applications for technology considered
important to the development of its business. The Company also relies upon trade
secrets, unpatented know-how, continuing technological innovation and the
aggressive pursuit of licensing opportunities to help develop and maintain its
competitive position.

     As of February 23, 2001, ATMI had been awarded 224 United States patents
and had 155 United States patent applications pending. Foreign counterparts of
certain of these applications have been filed, or may be filed at an appropriate
time. ATMI decides on a case-by-case basis whether, and in what countries, it
will file counterparts of a United States patent application outside the United
States. ATMI's United States patents expire between 2006 and 2020. ATMI also
holds 23 United States registered trademarks. ATMI is actively using all United
States trademarks.

     ATMI's ability to compete effectively with other companies will depend, in
part, on its ability to maintain the proprietary nature of its technology.
Although the Company has been awarded, has filed applications for, or has been
licensed under numerous patents in the United States and other countries, there
can be no assurance concerning the degree of protection afforded by these
patents or the likelihood that pending patents will be issued.

     ATMI requires all employees and most consultants, outside scientific
collaborators, sponsored researchers and other advisors to execute
confidentiality agreements upon the commencement of employment or consulting
relationships with the Company. These agreements provide that all confidential
information developed or made known to the individual during the course of the
individual's relationship with ATMI is to be kept confidential and not disclosed
to third parties except in specific circumstances. All of ATMI's employees have
entered into agreements providing for the assignment of rights to inventions
made by them while employed by the Company.

Environmental Regulation

     ATMI uses, generates and discharges toxic, volatile or otherwise hazardous
chemicals and wastes in its manufacturing, processing, and research and
development activities. As a result, the Company is subject to a variety of
governmental regulations related to the storage, use and disposal of these
materials. ATMI's failure to comply with present or future laws could result in
fines or other liabilities being imposed on the Company, suspension of
production or acessation of operations.

     The various premises, particularly the premises in Danbury, Connecticut,
may have been contaminated prior to occupancy. ATMI is not aware of any
environmental investigation or action by government agencies involving these
premises. However, under federal and state statutes and regulations, a
government agency may seek to recover its response costs and/or require future
remedial measures from both operators and owners of property where releases of
hazardous substances have occurred or are ongoing. The prior occupant of the
Danbury, Connecticut premises has agreed to indemnify ATMI for remediation costs
in connection with any pre-existing, on-site contamination or environmental
condition. However, this indemnification may not prove adequate to cover any
liability imposed on the Company related to the environmental condition of the
premises or the cost of defending an environmental action, either of which could
be substantial.

     ATMI's activities may also result in the Company's being subject to
additional regulation. Such regulations could require ATMI to acquire
significant additional equipment or to incur other substantial expenses to
comply with environmental laws. ATMI's failure to control the use of hazardous
substances could subject the Company to substantial financial liabilities.

                                      14
<PAGE>

Employees

     As of December 31, 2000, ATMI employed a total of 1,203 individuals,
including 430 in sales and administration, 582 in operations and 191 in research
and development. Of these employees, 44 hold Ph.D. degrees and 89 hold other
advanced degrees in electrical engineering, materials science, chemistry,
physics or related fields. None of the Company's employees are covered by
collective bargaining agreements. ATMI has not experienced any work stoppages,
and considers its relations with its employees to be good.

     ATMI will reduce its workforce in administrative, operational, and sales
functions by approximately 10% as part of the restructuring efforts in 2001.

Item 2.  Properties

     The following table summarizes the location and size of ATMI's various
properties as of December 31, 2000, other than headquarters.

<TABLE>
<CAPTION>
    ------------------- ------------------------- ---------------------- -----------------------
                                Location             Square Footage           Lease / Own
                        ------------------------- ---------------------- -----------------------
<S>                     <C>                       <C>                    <C>
                        Bloomington, MN                     70,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Burnet, TX                          30,000                    Own
                        ------------------------- ---------------------- -----------------------
        Materials       Carrollton, TX                      30,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Milpitas, CA                        12,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Anseong, South Korea                 9,000                    Own
                        ------------------------- ---------------------- -----------------------
                        Hoegaarden, Belgium                 30,000                    Own
                        ------------------------- ---------------------- -----------------------
                        Buffalo Grove, IL                   33,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Dallas, TX                          40,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Mesa, AZ                            33,000                    Own
                        ------------------------- ---------------------- -----------------------
                        Napa, CA                            40,000                    Own
                        ------------------------- ---------------------- -----------------------
                        Phoenix, AZ                         57,000                  Lease
                        ------------------------- ---------------------- -----------------------
       Technologies     Portland, OR                        12,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Albuquerque, NM                     12,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        San Jose, CA                        45,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Bonn, Germany                       12,000                    Own
                        ------------------------- ---------------------- -----------------------
                        Liexlip, Ireland                     8,000                  Lease
                        ------------------------- ---------------------- -----------------------
                        Munich, Germany                     30,000                    Own
                        ------------------------- ---------------------- -----------------------
                        Seoul, South Korea                   3,000                  Lease
----------------------- ------------------------- ---------------------- -----------------------
</TABLE>

     The Corporate Headquarters is located in Danbury, Connecticut, and the
facility is also utilized by both the Materials and Technologies operating
segments. The facility contains 72,000 square feet, and is subject to a lease
commitment. Additionally, in 2001, the Company has entered into a lease for an
additional 30,000 square feet in Danbury, Connecticut.

     The Company is constructing a manufacturing plant of approximately 71,000
square feet for expansion of its operations in Burnet, TX and consolidation of
the existing Burnet and Carrollton, TX facilities. Construction of the facility
should be completed by mid-year, 2002.

     ATMI will close the Buffalo Grove, IL and Milpitas, CA facilities and
will reduce space requirements in certain existing facilities as part of the
restructuring efforts in 2001.

Item 3.  Legal Proceedings

     ATMI has been notified by the Internal Revenue Service of an assessment of
$2.1 million for certain tax matters related to Advanced Delivery and Chemical
Systems subsidiary. Although ATMI believes that this assessment is without merit
and intends to vigorously defend its position on these tax matters, the Company
cannot predict whether it will be successful in defending against the assessment
or the amount of any final assessment against the Company.


                                      15
<PAGE>

     In December 1998, a former office employee of ADCS initiated a legal
proceeding against ADCS and ATMI in the District Court for the 33rd District in
Burnet, Texas, alleging personal injuries to her minor child (then unborn)
allegedly resulting from her exposure to various chemicals while employed by
ADCS. ATMI at all times denied the plaintiffs' legal allegations and vigorously
defended this action. On July 25, 2000, this lawsuit was dismissed with
prejudice by agreement of the parties, without any liability on the part of ADCS
and ATMI.

     In July 1999, ATMI filed suit against a company, alleging infringement of
certain liquid delivery system patents. Later in 1999, that company filed suit
against ATMI alleging infringement of a particular semiconductor process patent.
In January 2001, a letter of intent was executed that addressed the settlement
of both claims. Details of the settlement are currently being finalized, the
terms of which will have no material adverse effect on ATMI.

     In addition, in the normal course of business, ATMI is involved in various
lawsuits and claims. Although the Company cannot determine the ultimate outcome
of any of these legal proceedings at this time, management, including internal
counsel, does not believe that the outcome of these proceedings, individually or
in the aggregate, will have a material adverse effect on ATMI's financial
position or overall trends in results of operations.

Item 4. Submission of Matters to a Vote of Security Holders.

     No matter was submitted to a vote of security holders, through the
solicitation of proxies or otherwise, during the fourth quarter of the fiscal
year ended December 31, 2000.

Item 4A. Executive Officers of the Registrant.

     The executive officers of ATMI are as follows:

<TABLE>
<CAPTION>
Name                                          Age    Position
----                                          ---    --------
<S>                                           <C>    <C>
Eugene G. Banucci, Ph.D.....................   57    Chief Executive Officer, Chairman of the Board, and
                                                     Director
Douglas A. Neugold..........................   42    President
Daniel P. Sharkey...........................   44    Vice President, Chief Financial Officer, and Treasurer
</TABLE>

     Eugene G. Banucci, Ph.D., a founder of ATMI, has served as Chief Executive
Officer, Chairman of the Board and Director since 1986. Previously, Dr. Banucci
served in a variety of executive and managerial positions. From 1984 to 1986, he
was a director of American Cyanamid Company's Chemical Research Division, with
responsibility for the research, development and technical service activities of
the Chemicals Group.

     Douglas A. Neugold has served as President since May 2000. Until his
appointment as President, Mr. Neugold served as Executive Vice President of the
ATMI Materials segment since February 1999. In January 1998, Mr. Neugold joined
ATMI as Vice President of the NovaSource division, and since July 1998 served as
President of that division. Previously, Mr. Neugold served in a variety of
executive and managerial positions with the Electronic Materials Division of
Johnson Matthey. From 1995 to 1997, he served as Vice President, and later as
President of the Semiconductor Packages business. From 1993 to 1995, Mr. Neugold
served as Director of Asian Operations, and prior to that served in a variety of
business and marketing management positions focused on semiconductor technology.

     Daniel P. Sharkey has served as Chief Financial Officer since joining ATMI
in 1990, and has served as Vice President and Treasurer since 1993. From 1987 to
1990, Mr. Sharkey was Vice President of Finance and Administration for Adage,
Inc., a manufacturer of high-performance computer graphics terminals. From 1983
to 1987, he was Corporate Controller for CGX Corporation. Previously, Mr.
Sharkey served as Audit Supervisor for KPMG Peat Marwick.

         Executive officers serve at the discretion of the Board of Directors.
There are no family relationships among any of the executive officers or
directors.


                                      16
<PAGE>

                                   PART II.

Item 5.  Market for Registrant's Common Equity and Related Stockholder Matters.

     The Common Stock of ATMI has traded on the Nasdaq National Market under the
symbol ATMI since October 13, 1997. The following table sets forth for the
periods indicated the high and low sales price for the Common Stock as reported
on the Nasdaq National Market:

                                                          High       Low
                                                          ----       ---
     Fiscal year ended December 31, 1999
          1/st/ Quarter.............................    $ 31.00    $ 16.88
          2/nd/ Quarter.............................      30.00      18.25
          3/rd/ Quarter.............................      38.00      27.50
          4/th/ Quarter.............................      38.00      20.81
     Fiscal year ended December 31, 2000
          1/st/ Quarter.............................      60.75      29.13
          2/nd/ Quarter.............................      50.50      31.38
          3/rd/ Quarter.............................      50.00      20.00
          4/th/ Quarter.............................      24.31      14.38

     As of March 6, 2001, there were approximately 296 holders of record of the
Common Stock.

     The Company has never declared or paid any cash dividends on its capital
stock. The Company currently intends to retain all available earnings for use in
its business and does not anticipate paying any cash dividends in the
foreseeable future. Certain financing agreements of the Company's subsidiaries
contain limitations or prohibitions on the payment of dividends without the
lender's consent or in conjunction with a subsidiary's failure to comply with
various financial covenants.

     The Transfer Agent and Registrar for ATMI Common Stock is Boston Equiserve.


                                      17
<PAGE>

Item 6.   Selected Financial Data.

     The following selected consolidated statements of income for the years
ended December 31, 2000, 1999, 1998, 1997 and 1996 and the consolidated balance
sheet data as of December 31, 2000, 1999, and 1998 are derived from the audited
consolidated financial statements of ATMI, Inc. ("ATMI" or the "Company"). The
balance sheet data as of December 31, 1997 and 1996 is derived from unaudited
consolidated financial statements. The unaudited consolidated financial
statements include all adjustments, consisting of normal recurring accruals,
which the Company considers necessary for a fair presentation of the financial
position and the results of operations for these periods. The data set forth
below should be read in conjunction with the consolidated financial statements
and notes thereto and other financial information included elsewhere in this
Form 10-K.

<TABLE>
<CAPTION>
                                                                     Fiscal Year Ended December 31,
                                                                     ------------------------------
                                                          2000         1999         1998        1997         1996
                                                         ------       ------       ------       -----       ------
                                                                   (in thousands, except per share data)
<S>                                                    <C>          <C>           <C>        <C>            <C>
Consolidated Statements of Income:
    Revenues .......................................   $299,960     $202,506      $168,061   $192,381       $154,390
    Cost of revenues................................    142,711       95,456        84,864     92,658         73,673
                                                       ----------------------------------------------------------------
    Gross profit....................................    157,249      107,050        83,197     99,723         80,717
    Operating expenses:
        Research and development....................     28,211       18,359        16,630     14,336         12,314
        Selling, general and administrative.........     71,928       63,820 (3)    59,093     60,920         48,435
        Merger costs and related expenses...........      1,500 (1)    9,914 (4)     1,700 (5)  9,000 (6)      2,000 (7)
                                                       ----------------------------------------------------------------
           Total operating expenses.................    101,639       92,093        77,423     84,256         62,749
                                                       ----------------------------------------------------------------
    Operating income................................     55,610       14,957         5,774     15,467         17,968
    Interest income (expense), net..................      6,599        3,117         2,487       (912)          (375)
    Other income, net...............................      8,313 (2)      733           539        340             94
                                                       ----------------------------------------------------------------
    Income before income taxes and minority
       interest.....................................     70,522       18,807         8,800     14,895         17,687
    Provision for income taxes......................     26,486        7,720         4,412      8,588          4,745
                                                       ----------------------------------------------------------------
    Income before minority interest.................     44,036       11,087         4,388      6,307         12,942
    Minority interest...............................       (351)        (263)         (111)        (2)           151
                                                       ----------------------------------------------------------------
    Net income......................................   $ 43,685     $ 10,824      $  4,277   $  6,305       $ 13,093 (8)
                                                       ================================================================
    Net income per share--assuming dilution.........   $   1.44     $   0.38      $   0.15   $   0.24       $   0.54 (8)
                                                       ================================================================
    Weighted average shares
       outstanding--assuming dilution...............     30,290       28,689        27,793     26,030         24,318

<CAPTION>
                                                                              December 31,
                                                                              ------------
                                                            2000         1999       1998      1997         1996
                                                           ------       ------     ------   -------      -------
                                                                               (in thousands)
<S>                                                    <C>           <C>          <C>       <C>        <C>
Consolidated Balance Sheet Data:
    Cash, cash equivalents and marketable
    securities...............................          $ 131,505     $  92,328    $  86,253 $  32,949  $  35,966
    Working capital..........................            202,960       121,289      104,177    48,987     37,118
    Total assets.............................            350,805       228,849      210,617   154,456    125,873
    Long-term debt, less current portion.....              7,242         6,319       12,572    19,763     18,499
    Minority interest........................                  -         1,109          846       595        545
    Total stockholders' equity...............            286,567       176,356      154,306    84,170     66,049
</TABLE>

(1)    Represents cost incurred in connection with completing the
       Environmentally Safe Cleaning Alternatives, Inc. ("ESCA") acquisition.
(2)    Includes $9.5 million gain on sale of certain marketable securities in
       the first quarter of 2000, offset by a loss of $1.3 million in the same
       quarter on certain other investments.
(3)    Includes $2.3 million of severance expense for several former executives.
(4)    Represents $3.3 million incurred in connection with the completion of the
       acquisitions of MST Analytics and NewForm, and $7.2 million incurred in
       connection with the acquisitions of Delatech, Advanced Chemical Systems
       International, Inc. ("ACSI"), and Telosense offset by a reversal of $0.6
       million for previously accrued merger costs.
(5)    Represents costs incurred in connection with completing the NOW
       acquisition.
(6)    Represents costs incurred in investigating, analyzing and completing the
       Advanced Delivery and Chemical Systems Group ("ADCS Group") and Lawrence
       Semiconductor Laboratories ("LSL") acquisitions.
(7)    Represents $2.0 million ($1.2 million, net of taxes) accrued in
       connection with patent litigation involving LSL, which resulted in a
       settlement payment in May 1997.
(8)    Net income and net income per share--assuming dilution in 1996 include
       the effect of the ADCS Group's treatment as an S-Corporation for a
       portion of the year. If the ADCS Group had been taxed as a C-Corporation
       for all of 1996, the Company's net income and net income per
       share--assuming dilution would have been approximately $11.6 million and
       $0.48, respectively, for the year ended December 31, 1996.


                                      18
<PAGE>

Item 7.   Management's Discussion and Analysis of Financial Condition and
Results of Operations.

Overview

ATMI is a leading supplier of materials, equipment and related services used
worldwide in the manufacture of semiconductor devices. ATMI specifically targets
the "front-end" semiconductor materials market. This market includes the
processes used to convert a bare silicon wafer into a fully functional wafer
that contains many copies of a semiconductor device or "chip". ATMI's customers
include most of the leading semiconductor manufacturers in the world.

ATMI has organized its operations along two business segments: Materials and
Technologies. The Materials segment ("Materials") provides products that are
used in the semiconductor manufacturing process and related packaging and
delivery systems. The Technologies segment ("Technologies") provides products
and services that sense and environmentally control these materials while also
providing specialized thin film deposition and outsourced parts cleaning and
tool maintenance services to semiconductor device manufacturers. Technologies'
also conducts the Company's venture and government funded research and
development activities.

The semiconductor equipment industry is inherently cyclical. The Company's
equipment product lines are specifically tied to the semiconductor capital
spending cycles, which causes significant volatility in order and revenue
patterns for those products. Periods of robust capacity expansion are normally
followed by periods of capacity digestion when equipment spending slows and
existing capacity progresses towards full utilization. Following a strong period
of capital spending in 2000, the current outlook for 2001 is a decline in
capacity expansion within the industry followed by recovery in late 2001 or
early 2002. This will have a negative impact on the capital spending within the
industry during 2001 and ATMI's equipment product lines will be affected by that
trend.

The majority of ATMI's material product lines are driven by end use demand for
semiconductors, or how many devices are made, rather than the capacity needed to
make them. As such, these product lines are less cyclical. However, in 2001
there appears to be a softening in general macroeconomic conditions, causing a
reduced growth in demand for end-use devices. This general condition could have
an impact on the growth rate of ATMI's consumable product lines in 2001.

ATMI has completed eight acquisitions during the three years ended December 31,
2000, seven of which have been accounted for as pooling of interests. As a
result, the Company's consolidated financial statements have been restated to
reflect the results of these seven acquired companies. The 2000 acquisition of
the minority interest of its ADCS Korea joint venture was accounted for using
the purchase method of accounting.

Results of Operations

The following table sets forth selected financial data as a percentage of total
revenues for the periods indicated:

<TABLE>
<CAPTION>
                                                                                       Fiscal Year Ended December 31,
                                                                                       ------------------------------
                                                                                         2000     1999      1998
                                                                                         ----     ----      ----
   <S>                                                                                  <C>      <C>       <C>
    Revenues...........................................................................   100.0%   100.0%    100.0%
    Cost of revenues...................................................................    47.6     47.1      50.5
                                                                                          -----    -----     -----
    Gross profit.......................................................................    52.4     52.9      49.5
    Operating expenses:
     Research and development..........................................................     9.4      9.1       9.9
     Selling, general and administrative...............................................    24.0     31.5      35.2
     Merger costs and related expenses.................................................     0.5      4.9       1.0
                                                                                          -----    -----     -----
       Total operating expenses........................................................    33.9     45.5      46.1
                                                                                          -----    -----     -----
    Operating income...................................................................    18.5      7.4       3.4
    Interest income, net...............................................................     2.2      1.5       1.5
    Other income, net..................................................................     2.8      0.4       0.3
                                                                                          -----    -----     -----
    Income before income taxes and
     minority interest.................................................................    23.5      9.3       5.2
    Provision for income taxes.........................................................     8.8      3.8       2.6
                                                                                          -----    -----     -----
    Income before minority interest....................................................    14.7      5.5       2.6
    Minority interest..................................................................    (0.1)    (0.2)     (0.1)
                                                                                          -----    -----     -----
    Net income.........................................................................    14.6%     5.3%      2.5%
                                                                                          =====    =====     =====
</TABLE>


                                      19
<PAGE>
Segment Data

The Company has two reportable operating segments: Materials and Technologies.
The reportable operating segments are each managed separately because they
manufacture and distribute distinct products with different production
processes. The Company evaluates performance and allocates resources based on
segment operating profit or loss, excluding merger costs and related expenses,
interest, other income or expense, and income taxes. The accounting policies of
the reportable operating segments are the same as those described in the summary
of significant accounting policies in the Company's Consolidated Financial
Statements. Intercompany sales are not material among segments or operating
divisions.

The following tables provide reported results for each of these segments for the
periods indicated (in thousands):

<TABLE>
<CAPTION>
                                             Fiscal Year Ended December 31,
                                             ------------------------------
                                              2000       1999        1998
                                              ----       ----        ----
  <S>                                       <C>         <C>         <C>
   Revenues
   --------
   Materials...............................  $138,191   $ 96,711     $ 71,279
   Technologies............................   161,769    105,795       96,782
                                             --------   --------     --------
   Consolidated revenues...................  $299,960   $202,506     $168,061
                                             ========   ========     ========

   Operating Income
   ----------------
   Materials...............................  $ 36,655   $ 19,335     $ 11,373
   Technologies............................    20,455      5,536       (3,899)
   Merger costs and related expenses.......    (1,500)    (9,914)      (1,700)
                                             --------   --------     --------
   Consolidated operating income...........  $ 55,610   $ 14,957     $  5,774
                                             ========   ========     ========
</TABLE>

Comparison of Years Ended December 31, 2000, 1999 and 1998

Revenues. Revenues increased 48.1% to $300.0 million in 2000 from $202.5 million
in 1999, and increased 20.5% in 1999 from $168.1 million in 1998. The 2000
increase in revenues was primarily attributable to the continued growth of the
semiconductor industry during this time period, as well as increased market
penetration and the introduction of new products. Materials' revenues increased
42.9% in 2000 from 1999 levels, mainly as a result of increased market
penetration of gas delivery systems, and volume gains in materials, liquid
delivery systems and high purity packaging product lines. Technologies' revenues
increased 52.9% in 2000 from 1999 levels, led by significant growth in thin film
deposition services, the environmental and sensing product lines, and ATMI's
Emosyn business. The growth in sales between 1999 and 1998 was due in large part
to the recovery of the semiconductor industry from a cyclical downturn
experienced in 1998, particularly for consumable products, as seen by Materials'
35.7% growth in revenue. Materials experienced significant gains related to the
materials and delivery systems product lines and high purity packaging product
lines in 1999 as compared to 1998. Technologies' revenues for 1999 increased
9.3% from 1998 levels. Semiconductor manufacturing capacity expansion began to
rebound in the middle of 1999 leading to improved sales of environmental and
sensing products and thin film deposition services.

Gross Profit. Gross profit increased 46.9% to $157.2 million in 2000 from $107.1
in 1999. Gross margin decreased slightly to 52.4% in 2000 from 52.9% in 1999.
The decrease was due in large part to factors within the Technologies segment:
End-of-year softness in the environmental sensing and abatement equipment
product lines, manufacturing inefficiencies in thin film deposition services due
to the addition and continued ramp-up of manufacturing capacity to support
growth, and a higher percentage of total revenues generated by the Emosyn
business, which operates at lower margins than other ATMI businesses and product
lines. Partially offsetting these declines were favorable product mix shifts in
the high purity packaging product lines, and materials and delivery systems in
the Materials segment. Gross profit increased 28.7% to $107.1 million in 1999
from $83.2 million in 1998. Gross margin increased to 52.9% in 1999 from 49.5%
in 1998. This increase was due principally to margin growth related to
manufacturing efficiencies from increased sales and a shift in product mix
towards materials and delivery systems, high purity packaging and liquid
materials product lines.

Research and Development Expenses. Research and development expenses increased
53.7% to $28.2 million in 2000 from $18.4 million in 1999. The increase
represents the Company's continued efforts to develop advanced materials,
including development efforts on the SDS and chemicals product lines, and
continued development work in the sensing and abatement product lines.
Additionally, the Company continued to support development efforts in the Emosyn
venture. As a percentage of revenues, research and development spending remains
relatively flat at 9.4% in 2000 compared to 9.1% in 1999. Research and
development expenses increased 10.4% to $18.4 million in 1999 from $16.6 million
in 1998. Increased efforts to expand SDS technology beyond ion implant
applications into CVD, etch and bulk gas delivery, and continued product
development activities within Materials and the Emosyn venture resulted in
growth of the research and development efforts. As a percentage of revenues,
research and development expenses decreased to 9.1% in 1999 from 9.9% in 1998.

                                      20
<PAGE>

Selling, General and Administrative Expenses. Selling, general and
administrative expenses increased 12.7% to $71.9 million in 2000 from $63.8
million in 1999. As a percentage of revenues, these expenses declined to 24.0%
in 2000 from 31.5% in 1999. The decrease, as a percentage of revenues, was due
to decreased administrative costs resulting from continued cost savings
initiatives tied to the integration activities of business acquisitions, and the
decrease in executive compensation paid to members of management of certain
acquired businesses. Offsetting the cost savings were increases in legal costs
associated with defending and protecting the Company's intellectual property,
costs associated with implementation of an enterprise-wide information system,
and a full year of costs of operating the Company's new Asian sales and
distribution facilities. Selling, general and administrative expenses increased
8.0% to $63.8 million in 1999 from $59.1 million in 1998. Despite decreases in
expenses associated with decreased administrative costs and cost savings
resulting from the integration of recent business acquisitions, expenses
associated with the organization of the Company's Taiwanese subsidiary and the
commencement of the Company's enterprise-wide information system implementation
caused selling, general and administrative expenses to increase in 1999.
Additionally, the 1999 expenses included $2.3 million in severance for several
former executives. As a percentage of revenues, these expenses decreased to
31.5% in 1999 from 35.2% in 1998.

Merger Costs and Related Expenses. The 2000 operating results include $1.5
million of merger and related costs incurred in connection with professional
fees and transaction costs related to the July 2000 ESCA acquisition. The 1999
operating results included merger and related costs of $9.9 million, including
$3.3 million of professional fees and transactions costs related to the November
1999 acquisitions of MST and Newform and $2.8 million of investment banking
fees, legal fees and accounting fees in connection with the investigation,
analysis and May 1999 closing of the TeloSense, Delatech and ACSI transactions.
The 1999 merger related costs also included a $0.6 million reversal of
previously accrued merger costs for prior acquisitions. The acquisition of
Delatech also resulted in a $4.4 million asset impairment charge during the
second quarter of 1999 for inventory ($1.0 million) and goodwill ($3.4 million)
associated with an existing environmental equipment product line which was
determined to be impaired. The 1998 operating results included merger and
related costs of $1.7 million incurred in connection with the acquisition of NOW
Technologies.

Operating Income. Operating income, including the recognition of merger and
related costs, increased almost four fold to $55.6 million in 2000 from $15.0
million in 1999. As a percentage of revenues, operating income increased to
18.5% in 2000 compared to 7.4% in 1999. The revenue growth experienced in 2000
drove considerable operating income increases. Operating income, including the
recognition of merger and related costs, increased 159.0% in 1999 to $15.0
million from $5.8 million in 1998. Materials' operating income increased 90% to
$36.7 million in 2000 from $19.3 million in 1999. The increase was driven by
increased market penetration of gas delivery systems, volume gains in
materials, liquid delivery systems and high purity packaging product lines, and
improved leveraging of Materials' fixed overhead structure. Materials' operating
income for 1999 increased 70.0% to $19.3 million from $11.4 million in 1998.
This increase reflected the gains made due to the improved market conditions
within the industry and increased market penetration during 1999. The
significant revenue increase in 1999 combined with stronger margins and cost
containment initiatives resulted in higher operating income within Materials.
Materials' operating income, as a percentage of revenues, was 26.5%, 20.0% and
16.0% for 2000, 1999 and 1998, respectively. Technologies' operating income
increased to $20.5 million in 2000, from $5.5 million in 1999. The increase was
driven by significant growth in thin film deposition services, the environmental
and sensing product lines, and ATMI's Emosyn business, and increased operating
leverage through a focus on overhead cost reduction in this segment.
Technologies' operating income improved to $5.5 million in 1999, compared to a
$3.9 million loss in 1998. The profitability increase was attributable to the
growth in both environmental and sensing products and thin film deposition
services revenues, the attendant product margin improvements and a favorable
product mix shift along with an improvement in profitability of various contract
programs. Investments in research and product development within Emosyn and the
Company's other ventures are reflected in Technologies' operating income.
Technologies' operating income (loss), as a percentage of revenues, was 12.6%,
5.2% and (4.0)% in 2000, 1999 and 1998, respectively.

Other and Interest Income, Net. Other and interest income, net, increased to
$14.9 million in 2000 from $3.9 million in 1999. In 2000, other income included
a gain of approximately $9.5 million on the sale of certain marketable equity
securities by the Company, offset by a write-off of a $1.3 million cost basis
investment. Interest income increased to $7.8 million in 2000 from $4.4 million
in 1999 due to proceeds received of approximately $63.5 million related to the
Company's public stock offering in April 2000 and increased cash balances
derived from improved operating results of the Company. Other and interest
income, net increased to approximately $3.9 million in 1999 from $3.0 million in
1998. The increase in 1999 related to a significant increase in interest income
due to increased cash levels on hand throughout all of 1999 compared to only
part of 1998. These increased cash levels resulted from a public stock offering
that was completed at the beginning of the second quarter of 1998. An increase
in interest rates in 1999 also resulted in increased interest income. Interest
expense declined in 1999 due to lower levels of debt outstanding at December 31,
1999 compared to December 31, 1998. Interest expense decreased 26.5% to $1.3
million in 1999 from $1.7 million in 1998.


                                      21
<PAGE>

Income Taxes. Income tax expense increased 244% to $26.5 million in 2000 from
$7.7 million in 1999. Income tax expense increased 75.0% to $7.7 million in 1999
from $4.4 million in 1998. The 2000 effective tax rate of 37.6% differs from the
Federal statutory tax rate of 35% primarily because of state and foreign income
taxes, foreign sales corporation benefits, and non-deductible merger and
acquisition costs. The 1999 effective tax rate was 41%. The decline in the
effective rate in 2000 is based on the fact that there was a declining impact of
acquired companies' historic tax rates on restated financial statements in the
current year. The company incurred non-deductible merger costs in 1999 and
recognized benefit based on changes in estimates regarding the realizability of
net operating loss and tax credit carryforwards of certain acquired companies.
The 1998 effective tax rate of 50.1% was higher than statutory rates because no
tax benefit was recognized for the merger costs related to the NOW acquisition,
and no tax benefit was recognized for operating losses sustained by ACSI.

Minority Interest. Minority interest represented the 30.0% interest held by K.C.
Tech Co., Ltd. in the operations of ADCS-Korea, which was a joint venture
established to manufacture, sell and distribute chemicals to the semiconductor
and related industries in South Korea, in which ATMI had the remaining interest.
On December 28, 2000, ATMI purchased K.C. Tech Co., Ltd.'s 30% interest in the
operations of ADCS-Korea.

Net Income Excluding Merger Related Costs, Other Expenses, and One-Time Gains.
Over the last three years, the Company has used mergers and acquisitions to
accelerate its growth and broaden its product lines. As a result of this
strategy, the Company has incurred expenses to consummate these transactions and
integrate these acquired businesses into existing operations. Excluding merger
and related costs pursuant to acquisitions, certain severance charges related to
reorganizing the business pursuant to these acquisitions, and one-time gains
associated with the sale of certain securities, net income would have been $40.0
million, or $1.32 per share-assuming dilution in 2000, an increase of 104.0%
over $19.6 million, or $0.68 per share-assuming dilution in 1999. The 1999
amount represents a 211.1% increase over $6.3 million, or $0.23 per share-
assuming dilution in 1998. Weighted average shares outstanding assuming dilution
increased to 30.3 million shares for the year ended December 31, 2000, from 28.7
million shares for the year ended December 31, 1999, which was an increase from
27.8 million shares for the year ended December 31, 1998. The increase in 2000
primarily resulted from the completion of the April 4, 2000 public offering of
1.5 million shares.

Liquidity and Capital Resources

Years ended December 31, 2000, 1999 and 1998

To date, ATMI has financed its activities principally through cash from
operations, the sale of equity, external research and development funding and
various lease and debt instruments. The Company's working capital increased to
$203.0 million at December 31, 2000 from $121.3 million at December 31, 1999 and
$104.2 million at December 31, 1998.

Net cash provided by operations was approximately $9.1 million during 2000, as
compared to cash provided by operations of $13.2 million during 1999, and $13.0
million in 1998. The cash flow from operations for 2000 resulted primarily from
improvements in operating results, substantially offset by increased working
capital requirements--mainly accounts receivable and inventory. In addition, the
$1.5 million of merger costs in 2000 reduced the cash generated from operations
by approximately $1.0 million, with approximately $0.5 million remaining unpaid
at December 31, 2000. In 1999, operating cash flows improvement was driven
primarily from an improvement in operating results, partially offset by
increases in working capital accounts and deferred taxes. In addition, the $9.9
million of merger costs and related expenses in 1999 reduced the cash generated
from operations by approximately $4.3 million, as $4.4 million were non-cash
charges and approximately $1.2 million remained unpaid at December 31, 1999. The
$1.7 million of merger costs and related expenses incurred in the third quarter
of 1998, reduced the cash generated from operations by approximately $1.1
million, as approximately $0.6 million remained unpaid at December 31, 1998.

Net cash used by investing activities was $23.9 million in 2000, compared to
$10.7 used in 1999, and $18.0 million used in 1998. In 2000, the Company sold
marketable securities and received net proceeds of $10.6 million for future
working capital requirements. On December 28, 2000, the Company purchased K.C.
Tech Co., Ltd's 30% interest in the operations of ADCS-Korea for approximately
$7.2 million, of which $5.0 million was paid in 2000. Investing activities also
included capital expenditures of $29.5 million, $10.7 million, and $15.7 million
in the years 2000, 1999 and 1998, respectively. The 2000 expenditures were made
primarily to support growth in several of the Company's core businesses,
including epitaxial deposition services, liquid delivery systems, environmental
and sensing products, and in the company-wide enterprise information system. The
1999 expenditures were made primarily to support the growth experienced at
several of the Company's manufacturing facilities. The 1998 expenditures
primarily related to installation of additional manufacturing capacity in
Danbury, Connecticut, San Jose, California and the Company's two Texas
facilities. Among other investing activities, in 1998 ATMI invested
approximately $2.2 million into marketable securities as part of a strategic
business agreement.

                                      22
<PAGE>

Net cash provided by financing activities was $64.1 million in 2000. During
2000, the Company completed a registered underwritten public stock offering of
2,800,000 shares of the Company's common stock. Of such shares, the Company sold
1,500,000 shares and certain stockholders sold 1,300,000 shares. The Company
received net proceeds from the offering of approximately $63.4 million. Net cash
used by financing activities was $8.6 million in 1999, and net cash provided by
financing activities was $56.7 million in 1998. ATMI's financing activities
included a March 1998 registered underwritten public offering of 2,257,000
shares of its common stock. ATMI received net proceeds from the offering of
approximately $62.4 million. During 2000 and 1999, the Company made payments on
capital leases of approximately $2.7 million and $2.5 million, respectively. In
2000, the Company made $2.9 million of note payments and during 1999 the
Company made payments on notes of approximately $9.6 million, including the
retirement of a mortgage on the Mesa, Arizona facility. The Company's high
purity packaging business has an industrial revenue bond arrangement outstanding
in the amount of $1.9 million, which was used for equipment and improvements at
its manufacturing facility and corporate office. At December 31, 2000, $7.2
million of loans, bonds and financing remained outstanding. On March 27, 2001,
the Company entered into a $20.0 million financing arrangement for use in the
expansion of the Phoenix, Arizona facility. As of March 31, 2001, the Company
had drawn $8.7 million on this financing arrangement. Management believes that
the Company's debt service obligations can be adequately satisfied by cash flows
from operations.

ATMI believes that the Company's existing cash and cash equivalents and
marketable securities balances, existing sources of liquidity, available foreign
lines of credit and anticipated funds from operations will satisfy the Company's
projected working capital and other cash requirements through at least the end
of 2001. However, management also believes the level of financing resources
available to the Company is an important competitive factor in its industry and
management may seek additional capital prior to the end of that period.
Additionally, management considers, on a continuing basis, potential
acquisitions of technologies and businesses complementary to the Company's
current business. There are no present agreements with respect to any such
acquisitions. However, any such transactions may affect the Company's future
capital needs.

Operations Outside the United States

For the years ended December 31, 2000, 1999 and 1998, sales outside the United
States, including Asia and Europe, accounted for 45.0%, 38.9%, and 32.9%,
respectively, of the Company's revenues. Management anticipates that the
Company's sales outside the United States will continue to account for a
significant percentage of total revenues. The July 2000 acquisition of ESCA and
the November 1999 acquisitions of MST and Newform have increased the Company's
European operations. In addition, the Company has a wholly-owned subsidiary in
Taiwan where the Company sells and services several product lines. The Company
also has two wholly-owned subsidiaries in South Korea that manufacture, sell and
distribute environmental abatement equipment and thin-film materials to the
semiconductor and related industries in South Korea. Until December 2000, one of
the Company's subsidiaries in Korea, ADCS-Korea, was operated under a joint
venture agreement with K.C. Tech pursuant to which the Company had a 70.0%
interest. In December 2000, the Company purchased the remaining 30% interest in
ADCS-Korea from K.C. Tech.

Restructuring

On February 7, 2001, in response to softening industry conditions and the
Company's intent to more aggresively integrate previous acquisitions and reduce
costs of infrastructure, a restructuring initiative was announced. The Company
will take a pre-tax charge of approximately $9.0 million, which will be
recognized in the first quarter of 2001, to reflect this initiative, comprised
of the following: involuntary employee termination benefits; write-offs due to
asset impairments; and facility exit costs, including early lease termination
fees. This charge is anticipated to be funded with operating cash flows. The
project initiative will be carried out over twelve months and includes certain
facility closures and the related relocation of production assets, a reduction
in workforce in administrative, operational, and sales functions and the
outsourcing of non-core activities, as well as asset impairments related to
those initiatives. These actions are expected to result in a net employment
reduction of approximately 10% of the workforce.

Recent Accounting Pronouncements

Statement of Financial Accounting Standards ("SFAS") No. 133, "Accounting for
Derivative Instruments and Hedging Activities", as amended by SFAS Nos. 137 and
138, establishes standards for recognition and measurement of derivatives and
hedging activities. The adoption of the statement is required for the company in
the first quarter of fiscal year 2001. The Company does not believe the adoption
of SFAS No. 133 will have a material financial statement impact.

Forward-Looking Statements

The statements contained in this report which are not historical are "forward-
looking statements" within the meaning of Section 27A of the Securities Act of
1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as
amended. Examples of forward-looking statements include, without limitation,
statements by us regarding financial projections, expectations for demand and
sales of new and existing products, market and technology opportunities,
business strategies, business opportunities, objectives of management for future
operations and semiconductor industry and market segment growth. In addition,
when used in this report, the words "anticipate," "plan," "believe," "estimate,"
"expect" and similar expressions as they relate to us or our management are
intended to identify forward-looking statements. All forward-looking statements
involve risks and uncertainties. Actual results may differ

                                      23

<PAGE>

materially from those discussed in, or implied by, the forward-looking
statements as a result of certain factors including, but not limited to, changes
in the pattern of semiconductor industry growth, the markets for or customer
interest in our products, product and market competition, delays or problems in
the development and commercialization of products, problems or delays in
integrating acquired operations and businesses into ATMI, problems or delays
associated with its restructuring activity, and technological changes affecting
our competencies. The cautionary statements made in this report should be read
as being applicable to all related forward-looking statements wherever they
appear in this report.

Item 7A.          Quantitative and Qualitative Disclosures About Market Risk.

Interest Rate Risk

         As of December 31, 2000 the Company's cash and cash equivalents
included money market securities and commercial paper. Due to the short duration
of the Company's investment portfolio, an immediate 10% change in interest rates
would not have a material effect on the fair value of the Company's portfolio;
therefore, the Company would not expect the operating results or cash flows to
be affected to any significant degree by the effect of a sudden change in market
interest rates on the Company's securities portfolio.

Foreign Currency Exchange Risk

         A substantial portion of the Company's sales are denominated in U.S.
dollars and, as a result, the Company has relatively minimal exposure to foreign
currency exchange risk with respect to sales made. This exposure may change over
time as business practices evolve and could have a material impact on the
Company's financial results in the future. The Company does not use forward
exchange contracts to hedge exposures denominated in foreign currencies or any
other derivative financial instruments for trading or speculative purposes. The
effect of an immediate 10% change in exchange rates would not have a material
impact on the Company's future operating results or cash flows.

Item 8.           Financial Statements and Supplementary Data.

         The report of Independent Auditors, the consolidated financial
statements and the financial statement schedule that are listed in the Index to
Consolidated Financial Statements and Financial Statement Schedule are included
herein on pages F-1 through F-26.

Item 9.           Changes in and Disagreements with Accountants on Accounting
                  and Financial Disclosure.

     There have been no changes in or disagreements with accountants required to
be reported herein.

Item 10.          Directors and Executive Officers of the Registrant.

     Information regarding ATMI's directors is incorporated by reference herein
to the Company's Proxy Statement for its Annual Meeting of Stockholders to be
held on May 23, 2001 ("2001 Proxy Statement"). Information regarding ATMI's
executive officers is included as Item 4A in Part I of this Form 10-K.

Item 11.          Executive Compensation.

     Information regarding compensation of ATMI executive officers is
incorporated by reference herein to the 2001 Proxy Statement.

Item 12.          Security Ownership of Certain Beneficial Owners and
                  Management.

     Information regarding the beneficial ownership of shares of Common Stock of
the Company by certain persons is incorporated by reference herein to the 2001
Proxy Statement.

Item 13.          Certain Relationships and Related Transactions.

     Information regarding certain transactions of ATMI is incorporated by
reference herein to the 2001 Proxy Statement.

                                      24
<PAGE>

                                    PART IV


Item 14.          Exhibits, Financial Statement Schedule, and Reports on Form 8-
                  K.

  (a) The following documents are filed as part of this Annual Report on
      Form 10-K:

  (1) Financial Statements:

        Report of Independent Auditors
        Consolidated Balance Sheets - December 31, 2000 and 1999
        Consolidated Statements of Income for the years ended December 31,2000,
          1999, and 1998
        Consolidated Statements of Stockholders' Equity for the years ended
          December 31, 1998, 1999, and 2000
        Consolidated Statements of Cash Flows for the years ended December 31,
          2000,1999, and 1998
        Notes to Consolidated Financial Statements

  (2) Financial Statement Schedule:

        Schedule II Valuation and Qualifying Accounts

        The report of independent auditors, consolidated financial statements
        and financial statement schedule listed in the Index to Consolidated
        Financial Statements and Financial Statement Schedule on page F-1 hereof
        are filed as part of this report, commencing on page F-5 hereof.

        All other financial statement schedules are omitted as the required
        information is not applicable or the information is shown in the
        consolidated financial statements or related notes.

  (a) (3)  Exhibits

         Exhibit No.             Description
         -----------     --------------------------------------

      2.01              Agreement and Plan of Merger and Exchange by and among
                        AdvancedTechnology Materials, Inc., ATMI Holdings, Inc.,
                        Alamo Merger, Inc., Advanced Delivery & Chemical
                        SystemsNevada, Inc., Advanced Delivery & Chemical
                        Systems Manager, Inc.,Advanced Delivery & Chemical
                        Systems Holdings, LLC, AdvancedDelivery & Chemical
                        Systems Operating, LLC and Advanced Delivery& Chemical
                        Systems, Ltd. dated as of April 7, 1997 (Exhibit 2.01
                        toAdvanced Technology Materials, Inc. Quarterly Report
                        on Form 10-Q for the quarter ended June 30, 1997, File
                        No. 0-22756 ( "June 30, 1997 Form 10-Q ")). (1)

      2.03              Merger Agreement by and among ATMI, Inc., Glide
                        Acquisition, Inc. and NOW Technologies, Inc. dated as of
                        February 19, 1998 (Exhibit 2.03 to ATMI's Registration
                        Statement on Form S-1/A, dated March 3, 1998,
                        Registration No. 333-46609). (1)

      2.04              Agreement and Plan of Merger by and among Advanced
                        Chemical Systems International, Inc., ATMI, Inc. and
                        Strip Acquisition Corp. dated as of May 31, 1999
                        (Exhibit 2.1 to ATMI's Current Report on Form 8-K/A
                        dated June 15,1999, File No. 0-30130 ("June 1999 8-K")).
                        (1)

      2.05              Agreement and Plan of Merger by and among Delatech
                        Incorporated, ATMI, Inc. and Napa Acquistion Corp. and
                        certain shareholders of Delatech Incorporated dated as
                        of May 31, 1999 (Exhibit 2.2 to the June 1999 8-K). (1)

                                      25
<PAGE>

         Exhibit No.            Description
         -----------     --------------------------------------

      2.06              Agreement and Plan of Merger dated as of November 29,
                        1999 by and among, ATMI, Inc., and Fog Acquistion Corp.,
                        MST Analytics, Inc. and the Controlling Stockholders of
                        MST Analytics, Inc. as identified therein. (Exhibit 2.1
                        to ATMI's Current Report on Form 8-K/A, dated December
                        14,1999, File No. 0-30130). (1)

      3.01(a)           Certificate of Incorporation dated as of April 7, 1997
                        (Exhibit 3.01 to ATMI's Registration Statement on Form
                        S-4, dated September 10, 1997, Registration No. 333-
                        35323 (the "1997 Form S-4 Registration Statement ")).
                        (1)

      3.01(b)           Certificate of Amendment to Certificate of Incorporation
                        dated as of September 23, 1997 (Exhibit 4.1(b) to the
                        ATMI's Post-Effective Amendment No. 1 to Registration
                        Statement on Form S-8, filed October 10, 1997,
                        Registration No. 33-77060). (1)

      3.01(c)           Certificate of Amendment to Certificate of Incorporation
                        dated as of June 16, 1998 (Exhibit 3.01(c) to the ATMI's
                        Registration Statement on Form S-4/A, dated July 1,
                        1998, File No. 333-51333). (1)

      3.01(d)           Certificate of Designation for Series A Junior
                        Participating Preferred Stock dated as of October 13,
                        2000 (Exhibit 4.01 to ATMI's Current Report on Form 8-K
                        dated October 17, 2000). (1)

      3.02              Bylaws of ATMI (Exhibit 3.02 to the 1997 Form S-4
                        Registration Statement). (1)

      4.01              Specimen of the ATMI's Common Stock Certificate (Exhibit
                        4.01 to the 1997 Form S-4 Registration Statement). (1)

      4.02              Rights Agreement, dated as of October 13, 2000, between
                        ATMI, Inc. and Fleet National Bank, as Rights Agent
                        (Exhibit 4.01 to ATMI's Current Report on Form 8-K,
                        dated October 17, 2000). (1)

      10.01*            Employment Agreement between Eugene G. Banucci, Ph.D.
                        and Advanced Technology Materials, Inc. dated October
                        10, 1997 (Exhibit 10.01 to ATMI's Registration Statement
                        on Form S-1, dated February 20, 1998, File No. 333-46609
                        (the "Form S-1 Registration Statement")). (1)

      10.02*            Employment Agreement between Daniel P. Sharkey and
                        Advanced Technology Materials, Inc. dated October 10,
                        1997 (Exhibit 10.02 to the Form S-1 Registration
                        Statement). (1)

      10.03*            Employment Agreement between Douglas A. Neugold and
                        Advanced Technology Materials, Inc. dated April 26,
                        2000. (2)

      10.04             Agreement of Lease between Melvyn J. Powers and Mary P.
                        Powers d/b/a/ M&M Realty and Advanced Technology
                        Materials, Inc. dated December 23, 1994 (Exhibit 10.09
                        to Advanced Technology Materials, Inc. Annual Report on
                        Form 10-K/A for the year ended December 31, 1994, File
                        No. 0-22756). (1)

      10.05*            ATMI's 1995 Stock Plan (Exhibit to ATMI's
                        Registration Statement on Form S-8, File No. 33-93048).
                        (1)

      10.06*            ATMI's 1997 Stock Plan, dated October 10, 1997 (Exhibit
                        99.1 to ATMI's Registraton Statement on Form S-8, dated
                        April 6, 1998, File No. 333-49561). (1)

      10.07*            ATMI's 1998 Stock Plan, dated May 20, 1998 (Exhibit 99.1
                        to ATMI's Registration Statement on Form S-8, dated
                        June 2, 1998, File No. 333-56349). (1)

      10.08*            ATMI's 2000 Stock Plan, dated May 24, 2000 (Exhibit
                        99.01 to ATMI's Registration Statement on Form S-8,
                        dated September 20, 2000, File No. 333-46222). (1)

      21.01             Subsidiaries of ATMI (2)

      23.01             Consent of Ernst & Young LLP. (2)

      23.02             Consent of Arthur Andersen LLP (2)

      23.03             Consent of Rath, Anders, Dr. Wanner and Partner (2)

  *   Management contract or compensatory plan or arrangement.
 (1)  Incorporated by reference.
 (2)  Filed herewith.
b) Reports on Form 8-K
        The Company filed a Current Report on Form 8-K, dated October 17, 2000.

                                      26
<PAGE>

                                  SIGNATURES

         Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.
                                  ATMI, Inc.
                                  ---------
March 30, 2001
                                             By  /S/ Eugene G. Banucci
                                               --------------------------------
                                                     Eugene G. Banucci, Ph.D.,
                                           President, Chief Executive Officer,
                                           Chairman of the Board and Director

         Pursuant to the requirements of the Securities Exchange Act of 1934,
this report has been signed below by the following persons on behalf of the
registrant and in the capacities and on the dates indicated.

<TABLE>
<CAPTION>

Signature                                 Title                                     Date
---------                                 -----                                     ----
<S>                        <C>                                                     <C>
                            Chief Executive Officer, Chairman of the Board
/S/ Eugene G. Banucci       and Director (principal executive officer)              March 30, 2001
-------------------------
Eugene G. Banucci, Ph.D.
                            Vice President, Chief Financial
                            Officer and Treasurer (principal financial and
/S/ Daniel P. Sharkey       accounting officer)                                     March 30, 2001
-------------------------
Daniel P. Sharkey

/S/ Mark A. Adley                                                                   March 30, 2001
-------------------------
Mark A. Adley               Director

/S/ Robert S. Hillas                                                                March 30, 2001
-------------------------
Robert S. Hillas            Director

/S/ Stephen H. Mahle                                                                March 30, 2001
-------------------------
Stephen H. Mahle            Director

/S/ Michael J. Yomazzo                                                              March 30, 2001
-------------------------
Michael J. Yomazzo          Director

/S/ C. Douglas Marsh                                                                March 30, 2001
-------------------------
C. Douglas Marsh            Director
</TABLE>

                                      27
<PAGE>

                                  ATMI, INC.

      INDEX TO CONSOLIDATED FINANCIAL STATEMENTS AND FINANCIAL STATEMENT
                                   SCHEDULE

<TABLE>
<CAPTION>
                                                                                                     Page
                                                                                                     ----
<S>                                                                                                  <C>
  Report of Ernst & Young LLP.......................................................................  F-2
  Report of Arthur Andersen LLP.....................................................................  F-3
  Reports of Rath, Anders, Dr. Wanner and Partner (GbR) ............................................  F-4
  Audited Financial Statements......................................................................
  Consolidated Balance Sheets - December 31, 2000 and 1999..........................................  F-6
  Consolidated Statements of Income for the years ended December 31, 2000,
      1999, and 1998................................................................................  F-7
  Consolidated Statements of Stockholders' Equity for the years ended
      December 31, 1998, 1999, and 2000. ...........................................................  F-8
  Consolidated Statements of Cash Flows for the years ended December 31, 2000,
      1999, and 1998................................................................................  F-9
  Notes to Consolidated Financial Statements........................................................ F-10

  Financial Statement Schedule
  Schedule II - Valuation and Qualifying Accounts................................................... F-26
</TABLE>

                                       F-1
<PAGE>

                        Report of Independent Auditors

The Board of Directors and Stockholders of ATMI, Inc.

We have audited the accompanying consolidated balance sheets of ATMI, Inc. as of
December 31, 2000 and 1999, and the related consolidated statements of income,
stockholders' equity, and cash flows for each of the three years in the period
ended December 31, 2000. Our audits also included the financial statement
schedule listed in the Index at Item 14(a). These financial statements and
schedule are the responsibility of the management of ATMI, Inc. Our
responsibility is to express an opinion on these financial statements and
schedule based on our audits. We did not audit the financial statements of MST
Analytics, Inc. ("MST"), a wholly-owned subsidiary, for the year ended December
31, 1998, which statements reflect total revenues constituting 12% of the
consolidated total. Those statements were audited by other auditors whose
reports have been furnished to us, and our opinion, insofar as it relates to
data included for MST for the period indicated, is based solely on the reports
of such other auditors.

We conducted our audits in accordance with auditing standards generally accepted
in the United States. Those standards require that we plan and perform the audit
to obtain reasonable assurance about whether the financial statements are free
of material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant estimates
made by management, as well as evaluating the overall financial statement
presentation. We believe that our audits and the reports of other auditors
provide a reasonable basis for our opinion.

In our opinion, based on our audits and the reports of other auditors, the
financial statements referred to above present fairly, in all material respects,
the consolidated financial position of ATMI, Inc. at December 31, 2000 and 1999,
and the consolidated results of its operations and its cash flows for each of
the three years in the period ended December 31, 2000, in conformity with
accounting principles generally accepted in the United States. Also, in our
opinion, the related financial statement schedule, when considered in relation
to the basic financial statements taken as a whole, present fairly in all
material respects the information set forth therein.

                                                           /s/ ERNST & YOUNG LLP

Stamford, Connecticut
February 1, 2001

                                       F-2
<PAGE>

                   REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS

To the Board of Directors of MST Analytics, Inc.

We have audited the consolidated balance sheet of MST ANALYTICS, INC. (a
Delaware corporation) AND SUBSIDIARIES as of December 31, 1998, and the related
consolidated statements of operations, stockholders' equity and cash flows for
the year then ended. These financial statements are the responsibility of the
Company's management. Our responsibility is to express an opinion on these
financial statements based on our audit. We did not audit the financial
statements of MST Micro-Sensor-Technologies GmbH, Hohenschaftlarn and Sensoric
Gesellschaft fur angewandte Elektrochemie mbh & Co. KG, Hohenschaftlarn, wholly
and majority-owned subsidiaries, respectively, which statements reflect total
assets and total revenues of 55% and 47%, respectively, of the related
consolidated totals. Those statements were audited by other auditors whose
report has been furnished to us, and our opinion, insofar as it relates to the
amounts included for those entities, is solely based on the report of the other
auditors.

We conducted our audit in accordance with generally accepted auditing standards.
Those standards require that we plan and perform the audit to obtain reasonable
assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audit and the report of the other auditors provide a
reasonable basis for our opinion.

In our opinion, based on our audit and the report of other auditors, the
consolidated financial statements referred to above present fairly, in all
material respects, the financial position of MST Analytics, Inc. and
Subsidiaries as of December 31, 1998, and the results of their operations and
their cash flows for the year then ended, in conformity with generally accepted
accounting principles.

/s/ Arthur Andersen LLP
Chicago, Illinois
May 28, 1999

                                       F-3
<PAGE>

                                    OPINION

MST Micro-Sensor-Technologie GmbH Hohenschaftlarn, Germany

We have conducted a full audit of MST Micro-Sensor-Technologie GmbH,
Hohenschaftlarn, (in the following called "MST" or "Company"), expressed in
Deutsche Mark (DM), as of December 31, 1998.

(1) These financial statements are the responsibility of the Company's
management. Our responsibility is to express an opinion on these financial
statements based on our audit.

       (2) We have conducted our audit in accordance with generally accepted
       auditing standards in the United States. These standards require that we
       plan and perform the audit to obtain reasonable assurance about whether
       the financial statements are free of material misstatements. An audit
       includes examining, on a test basis, evidence supporting the amounts and
       disclosures in the financial statements. An audit also includes assessing
       the accounting principles used and significant estimates made by
       management, as well as evaluating the overall financial statement
       presentation. We believe that our audit provides a reasonable basis for
       our opinion.

       (3) The reporting package does not present all disclosures required under
       US- GAAP, e.g. no cash flow statement and no tax rationalization form
       have been prepared.

       (4) On the basis of our audit we certify that the documents attached to
       this clearance have been issued in compliance with the methods and
       principles accepted by US-GAAP.

       Munich, January 22, 1999
Rath, Anders, Dr. Wanner & Partner

/s/ Kabisch                                             /s/ Metzler

Dipl.-Kfm. Kabisch                                  Dipl.-Kfm. Metzler
Vereidigter Buchprufer                              Wirtschaftsprufer

                                       F-4
<PAGE>

                                    OPINION

Sensoric Gesellschaft fur angewandte Elektrochemie mbh Co. KG
Hohenschaftlarn

We have conducted a full audit of Sensoric Gesellschaft fur angewandte
Elektrochemie mbh & Co. KG, Hohenschaftlarn, (in the following called "Sensoric"
or "Company"), expressed in Deutsche Mark (DM), as of December 31, 1998.

(1) These financial statements are the responsibility of the Company's
management. Our responsibility is to express an opinion on these financial
statements based on our audit.

        (2) We have conducted our audit in accordance with generally accepted
        auditing standards in the United States. These standards require that we
        plan and perform the audit to obtain reasonable assurance about whether
        the financial statements are free of material misstatements. An audit
        includes examining, on a test basis, evidence supporting the amounts and
        disclosures in the financial statements. An audit also includes
        assessing the accounting principles used and significant estimates made
        by management, as well as evaluating the overall financial statement
        presentation. We believe that our audit provides a reasonable basis for
        our opinion.

        (3) The reporting package does not present all disclosures required
        under US-GAAP, e.g. no cash flow statement and no tax rationalization
        form have been prepared.

        (4) On the basis of our audit we certify that the documents attached to
        this clearance have been issued in compliance with the methods and
        principles accepted by US-GAAP.

       Munich, January 22, 1999
Rath, Anders, Dr. Wanner & Partner

/s/ Kabisch                                             /s/ Metzler

Dipl.-Kfm. Kabisch                                     Dipl.-Kfm. Metzler
Vereidigter Buchprufer                                 Wirtschaftsprufer

                                       F-5
<PAGE>

                                  ATMI, INC.

                          CONSOLIDATED BALANCE SHEETS

                     (in thousands, except per share data)


<TABLE>
<CAPTION>
                                                                                                                    December 31,
                                                                                                                    -----------
                                                                                                                  2000       1999
                                                                                                                  ----       ----
                                     ASSETS
<S>                                                                                                              <C>         <C>
Current assets:
  Cash and cash equivalents (Note 1)..........................................................................   $127,786    $78,640
  Marketable securities (Notes 1 and 2).......................................................................      3,719     13,688
  Accounts receivable, net of allowance for doubtful accounts of $1,725 in
    2000, and $1,366 in 1999 (Note 3).........................................................................     70,282     42,958
  Inventories (Notes 1 and 4).................................................................................     39,404     21,772
  Deferred income taxes (Note 8)..............................................................................      4,624        841
  Other.......................................................................................................     11,608      6,313
                                                                                                                 --------    -------
        Total current assets..................................................................................    257,423    164,212
Property, plant and equipment, net (Notes 1 and 5)............................................................     80,332     55,871
Goodwill and other long-term assets, net (Notes 1 and 11).....................................................     13,050      8,766
                                                                                                                 --------   --------
                                                                                                                 $350,805   $228,849
                                                                                                                 ========   ========

                                               LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
  Accounts payable............................................................................................   $ 23,161   $ 11,181
  Accrued liabilities.........................................................................................      8,078     10,272
  Accrued salaries and related benefits.......................................................................      9,764      9,341
  Loans, notes and bonds payable, current portion (Note 6)....................................................      5,101      5,601
  Capital lease obligations, current portion (Note 7).........................................................      2,733      1,936
  Income taxes payable (Note 8)...............................................................................      5,626      4,592
                                                                                                                 --------   --------
        Total current liabilities.............................................................................     54,463     42,923
Loans, notes and bonds payable, less current portion (Note 6).................................................      2,110      4,487
Capital lease obligations, less current portion (Note 7)......................................................      5,132      1,832
Deferred income taxes (Note 8)................................................................................      2,374      1,664
Other long-term liabilities...................................................................................        159        478
Minority interest (Note 11)...................................................................................          -      1,109
Commitments and contingencies (Note 14)
Stockholders' equity (Note 10):
  Preferred stock, par value $.01: 2,000 shares authorized; none issued.......................................          -          -
  Common stock, par value $.01: 50,000 shares authorized; 30,205 and 28,144 issued
    and outstanding in 2000 and 1999, respectively............................................................        302        281
  Additional paid-in capital..................................................................................    198,775    124,574
  Retained earnings...........................................................................................     88,585     44,995
  Accumulated other comprehensive income (loss) (Note 12).....................................................    (1,095)      6,506
                                                                                                                 --------   --------
        Total stockholders' equity............................................................................    286,567    176,356
                                                                                                                 --------   --------
                                                                                                                 $350,805   $228,849
                                                                                                                 ========   ========
</TABLE>

                            See accompanying notes.

                                      F-6
<PAGE>

                                  ATMI, INC.

                       CONSOLIDATED STATEMENTS OF INCOME

                     (in thousands, except per share data)

<TABLE>
<CAPTION>
                                                                                                       Year Ended December 31,
                                                                                                       -----------------------
                                                                                                    2000        1999        1998
                                                                                                    ----        ----        ----
<S>                                                                                                <C>         <C>         <C>
   Revenues (Notes 1 and 15).................................................................      $299,960    $202,506    $168,061
   Cost of revenues..........................................................................       142,711      95,456      84,864
                                                                                                   --------    --------    --------
   Gross profit..............................................................................       157,249     107,050      83,197
   Operating expenses:.......................................................................
       Research and development (Note 1).....................................................        28,211      18,359      16,630
       Selling, general and administrative (Note 13).........................................        71,928      63,820      59,093
       Merger costs and related expenses (Note 11)...........................................         1,500       9,914       1,700
                                                                                                   --------    --------    --------
                                                                                                    101,639      92,093      77,423
                                                                                                   --------    --------    --------
   Operating income..........................................................................        55,610      14,957       5,774
   Interest income...........................................................................         7,846       4,384       4,210
   Interest expense (Note 6).................................................................        (1,247)     (1,267)     (1,723)
   Other income, net (Note 1)................................................................         8,313         733         539
                                                                                                   --------    --------    --------
   Income before income taxes and minority interest..........................................        70,522      18,807       8,800
   Provision for income taxes (Note 8).......................................................        26,486       7,720       4,412
                                                                                                   --------    --------    --------
   Income before minority interest...........................................................        44,036      11,087       4,388
   Minority interest.........................................................................          (351)       (263)       (111)
                                                                                                   --------    --------    --------
   Net income (Note 15)......................................................................      $ 43,685    $ 10,824    $  4,277
                                                                                                   ========    ========    ========
   Net income per share--basic (Notes 1 and 10)..............................................         $1.51       $0.40       $0.16
                                                                                                   ========    ========    ========
   Net income per share--assuming dilution (Notes 1 and 10)..................................         $1.44       $0.38       $0.15
                                                                                                   ========    ========    ========
   Weighted average shares outstanding--basic (Notes 1 and 10)...............................        28,928      26,773      25,978
                                                                                                   ========    ========    ========
   Weighted average shares outstanding--assuming dilution (Notes 1 and 10)...................        30,290      28,689      27,793
                                                                                                   ========    ========    ========
</TABLE>

                            See accompanying notes.

                                      F-7
<PAGE>

                                  ATMI, INC.

                CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY

                                (in thousands)

<TABLE>
<CAPTION>
                                                                                                           Accumulated
                                                                                     Additional               Other
                                                                           Common     Paid-in   Retained  Comprehensive
                                                                            Stock     Capital   Earnings  Income (Loss)    Total
                                                                          ---------------------------------------------------------
<S>                                                                       <C>        <C>        <C>       <C>             <C>
Balance at December 31, 1997...........................................        $254   $ 54,814   $30,556       $(1,454)    $ 84,170
Issuance of 159 common shares pursuant to the
  exercise of employee stock options...................................           1        782        --             --         783
Issuance of common shares by pooled entity.............................          --      1,379        --             --       1,379
Sale of 2,257 common shares, net of issuance costs of $4,161...........          23     62,403        --             --      62,426
Compensation from the issuance of common shares........................          --        370        --             --         370
Tax benefit related to nonqualified stock options......................          --      1,099        --             --       1,099
Distributions to stockholders..........................................          --         --     (397)             --       (397)
Adjustment to reflect change in pooled entity fiscal year..............          --         --     (102)             --       (102)
Net income.............................................................          --         --     4,277             --       4,277
Unrealized loss on available-for-sale securities
  (net of tax benefit of $281).........................................          --         --        --          (500)       (500)
Cumulative translation adjustment......................................          --         --        --            801         801
                                                                                                                           --------
Comprehensive income...................................................                                                       4,578
                                                                          ---------------------------------------------------------
Balance at December 31, 1998...........................................         278    120,847    34,334        (1,153)     154,306
Issuance of 204 common shares pursuant to the
  exercise of employee stock options...................................           2      1,046        --             --       1,048
Issuance of 20 common shares pursuant to the
  exercise of warrants.................................................          --        222        --             --         222
Issuance of 64 common shares pursuant to the
  employee stock purchase plan.........................................           1        952        --             --         953
Issuance of common shares by pooled entity.............................          --         45        --             --          45
Distributions to stockholders..........................................          --      (338)        --             --       (338)
Compensation from the issuance of common shares........................          --        426        --             --         426
Tax benefit related to nonqualified stock options......................          --      1,374        --             --       1,374
Adjustment to reflect change in pooled entity fiscal year..............          --         --     (163)             --       (163)
Net income.............................................................          --         --    10,824             --      10,824
Unrealized gain on available-for-sale securities
  (net of tax provision of $4,141).....................................          --         --        --          7,860       7,860
Cumulative translation adjustment......................................          --         --        --          (201)       (201)
                                                                                                                           --------
Comprehensive income...................................................                                                      18,483
                                                                          ---------------------------------------------------------
Balance at December 31, 1999...........................................         281    124,574    44,995          6,506     176,356
                                                                          ---------------------------------------------------------
Issuance of 497 common shares pursuant to the
  exercise of employee stock options...................................           5      4,693        --             --       4,698
Issuance of 10 common shares pursuant to the
  exercise of warrants.................................................          --        112        --             --         112
Issuance of 55 common shares pursuant to the
  employee stock purchase plan.........................................           1      1,492        --             --       1,493
Sale of 1,500 common shares, net of issuance costs of $4,075...........          15     63,410        --             --      63,425
Compensation from the issuance of common shares........................          --         82        --             --          82
Tax benefit related to nonqualified stock options......................          --      4,412        --             --       4,412
Adjustment to reflect change in pooled entity
  fiscal year..........................................................          --         --      (95)             --        (95)
Net income.............................................................          --         --    43,685             --      43,685
Reclassification adjustment for realized gain on
  available-for-sale securities sold (net of tax provision of $2,161)..          --         --        --        (3,680)     (3,680)
Unrealized loss on available-for-sale securities
  (net of tax benefit of $1,618).......................................          --         --        --        (2,895)     (2,895)
Cumulative translation adjustment......................................          --         --        --        (1,026)     (1,026)
                                                                                                                           --------
Comprehensive income...................................................                                                      36,084
                                                                          ---------------------------------------------------------
Balance at December 31, 2000...........................................        $302   $198,775   $88,585       ($1,095)   $ 286,567
                                                                          ---------------------------------------------------------
</TABLE>

                            See accompanying notes.

                                      F-8
<PAGE>

                                  ATMI, INC.

                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                                (in thousands)

<TABLE>
<CAPTION>
                                                                                                         Year Ended December 31,
                                                                                                         -----------------------
                                                                                                         2000       1999     1998
                                                                                                         ----       ----     ----
<S>                                                                                                      <C>       <C>       <C>
Operating activities
Net income.........................................................................................    $  43,685 $  10,824 $  4,277
Adjustments to reconcile net income to net cash provided by
  operating activities:
  Depreciation and amortization....................................................................       12,787    11,256   10,263
  Write-down of goodwill...........................................................................            -     3,386        -
  Stock option compensation........................................................................           82       426      370
  Effect of change of fiscal year of pooled entity.................................................          (95)     (163)    (102)
  Realized gain on sale of investment..............................................................       (9,520)        -        -
  Write-down of investment.........................................................................        1,250         -        -
  Provision for bad debts..........................................................................          431       587      399
  Deferred income taxes............................................................................          985    (6,677)  (1,891)
  Tax benefit of nonqualified stock options........................................................        4,412     1,374    1,099
  Minority interest in net earnings of subsidiaries................................................          351       263      111
  Changes in operating assets and liabilities......................................................
    (Increase) decrease in accounts receivable.....................................................      (27,755)  (17,372)  10,284
    (Increase) in inventories......................................................................      (17,632)   (2,539)    (814)
    (Increase) decrease in other assets............................................................       (5,934)    1,259   (4,418)
    Increase (decrease) in accounts payable........................................................       11,980     1,811   (1,128)
    Increase (decrease) in accrued expenses........................................................       (5,401)    5,678   (4,767)
    Increase (decrease) in other liabilities.......................................................         (555)    3,077     (670)
                                                                                                       --------- --------- --------
      Net cash provided by operating activities....................................................        9,071    13,190   13,013
                                                                                                       --------- --------- --------
Investing activities
Capital expenditures...............................................................................      (29,520)  (10,716) (15,701)
Purchase of minority interest......................................................................       (5,000)        -        -
Long-term investment...............................................................................            -         -     (261)
Purchases of marketable securities.................................................................            -         -   (2,187)
Sales of marketable securities.....................................................................       10,612         -        -
Proceeds from sale of assets.......................................................................            -         -      199
                                                                                                       --------- --------- --------
      Net cash (used) by investing activities......................................................      (23,908)  (10,716) (17,950)
                                                                                                       --------- --------- --------
Financing activities
Borrowings from loans, notes, and bonds payable....................................................            -     1,544    2,971
Payments on capital lease obligations..............................................................       (2,742)   (2,477)  (2,846)
Payments on loans, notes, and bonds payable........................................................       (2,877)   (9,559)  (6,747)
Distributions to stockholders......................................................................            -      (338)    (397)
Proceeds from sale of common stock, net............................................................       63,425         -   62,426
Proceeds from sale of common and preferred stock by pooled entities................................            -         -      525
Proceeds from exercise of stock options, warrants and employee stock purchase plan shares..........        6,303     2,223      783
                                                                                                       --------- --------- --------
      Net cash (used) by financing activities......................................................       64,109    (8,607)  56,715
Effects of exchange rate changes on cash...........................................................         (126)      (74)     120
                                                                                                       --------- --------- --------
Net increase (decrease) in cash and cash equivalents...............................................       49,146    (6,207)  51,898
Cash and cash equivalents, beginning of year.......................................................       78,640    84,847   32,949
                                                                                                       --------- --------- --------
Cash and cash equivalents, end of year.............................................................    $ 127,786 $  78,640 $ 84,847
                                                                                                       ========= ========= ========
</TABLE>

                            See accompanying notes.

                                      F-9
<PAGE>

                                  ATMI, INC.

                  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.   Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements include the accounts of ATMI, Inc. and its
majority-owned subsidiaries, after elimination of intercompany accounts and
transactions.

Certain prior year amounts have been reclassified to conform to the current year
presentation.

Company's Activities

ATMI, Inc. together with its subsidiaries ("ATMI" or the "Company") is a leading
supplier of materials, equipment and related services used in the manufacture of
semiconductor devices. The Company specifically targets the "front end"
semiconductor materials market. The Company provides:

     .    a broad range of ultrahigh-purity semiconductor materials;
     .    semiconductor materials packaging and delivery systems;
     .    sensors for the workplace and environment that detect materials as
          they move through the workplace;
     .    point-of-use environmental equipment that abates materials;
     .    specialty thin film deposition services that provide coated wafers
          directly to customers; and
     .    outsourced parts cleaning and semiconductor fabrication tool
          maintenance.

Revenue Recognition

The Company's revenues from product sales are recognized upon title transfer,
which occurs upon shipment. A provision for the estimated cost of warranty is
recorded when revenue is recognized. Service revenue is recognized ratably over
the period of the related contract or, if not under contract, when service is
provided.

Use of Estimates

The preparation of the consolidated financial statements in conformity with
accounting principles generally accepted in the United States requires
management to make estimates and assumptions that affect the amounts reported in
the financial statements and accompanying notes. Actual results may differ from
those estimates, and such differences could be material to the financial
statements.

Risks and Uncertainties

Financial instruments that potentially subject the Company to significant
concentrations of credit risk consist primarily of cash, cash equivalents,
marketable securities, and accounts receivable. The Company places its cash,
cash equivalents, and marketable securities primarily in market rate accounts
and U.S. Treasury bills. The Company performs ongoing credit evaluations of its
customers' financial condition and generally requires no collateral from its
customers. The Company utilized one vendor to manufacture and distribute product
that accounted for approximately 14%, 13% and 10% of revenues in 2000, 1999 and
1998, respectively. The Company had amounts due from one customer that accounted
for approximately 16% and 14% of accounts receivable at December 31, 2000 and
1999, respectively.

Research and Development

Research and development costs primarily relate to self-funded projects and
include materials, labor, and overhead, and are expensed as incurred.

                                      F-10
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

1.   Summary of Significant Accounting Policies (continued)

Marketable Securities and Investments

Highly liquid investments with maturities of three months or less, when
purchased, are classified as cash and cash equivalents. Investments with
maturities greater than three months are classified as marketable securities.

In connection with its strategic alliances and research and development
activities, the Company has acquired equity securities of certain of its
alliance partners. The Company realized a $9.5 million gain on the sale of
certain marketable equity securities, offset by a loss of $1.3 million on a
certain other investment; these amounts are included in other income for the
year ended December 31, 2000.

The Company accounts for investments in accordance with Statement of Financial
Accounting Standards ("SFAS") No. 115, "Accounting for Certain Investments in
Debt and Equity Securities." The Company's policy, except for its equity
investments in alliance partners, is to protect the value of its investment
portfolio and to minimize principal risk by earning returns based on current
interest rates. All of the Company's marketable securities are classified as
available-for-sale as of the balance sheet date and are reported at fair value,
based on quoted market prices, with unrealized gains and losses recorded in
accumulated other comprehensive income, net of tax. The cost of securities sold
is based on the specific identification method. Interest on these securities is
accrued and included in interest income.

Management determines the classification of marketable debt securities at the
time of purchase and reevaluates such designation as of each balance sheet date.

Inventories

Inventories are stated at the lower of cost or market using the first- in,
first-out method.

Property, Plant and Equipment

Property and equipment is stated at cost. Depreciation and amortization of
property, plant and equipment is computed using the straight-line method over
the estimated useful lives of the assets as follows: buildings, twenty to forty
years; machinery and equipment, three to ten years; furniture and fixtures, five
to ten years; and leasehold improvements are amortized over the lease term.

Foreign Currency Translation

The Company's foreign subsidiaries operate primarily using local functional
currencies. Accordingly, all assets and liabilities of these subsidiaries are
translated using exchange rates in effect at the end of the period, and revenues
and expenses are translated using average exchange rates for the period. The
resulting translation adjustments are presented as a separate component of
accumulated other comprehensive income. Gains or losses resulting from foreign
currency transactions are included in other income (expense) and have not been
material.

Income Taxes

The Company accounts for income taxes in accordance with the liability method.
Under this method, deferred tax assets and liabilities are determined based upon
differences between the financial reporting and the tax basis of assets and
liabilities and are measured using the tax rates and laws that are expected to
be in effect when the differences are expected to reverse.

Fair Values of Financial Instruments

The Company's financial instruments consist primarily of cash, cash equivalents,
marketable securities, accounts receivable, accounts payable, and debt.
Marketable securities are accounted for at fair value. All other financial
instruments are accounted for on a historical cost basis, which due to the
nature of these instruments, approximates fair value at the balance sheet dates.

                                      F-11
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

1.    Summary of Significant Accounting Policies (continued)

Long-Lived Assets

The Company reviews on a periodic basis the value of its long-lived assets to
determine whether impairment exists. The Company assesses these assets for
impairment based on estimated future cash flows from these assets. In connection
with the acquisition of Delatech, the Company recorded a charge of $3.4 million
in 1999 associated with the impairment of goodwill related to an existing EcoSys
product line (see Note 11). This charge was based on the estimate of future cash
flows on a discounted basis compared with the carrying value of the goodwill.
Goodwill of $8.2 million and $4.0 million at December 31, 2000 and 1999 is
amortized over periods of ten to twenty years and is stated net of accumulated
amortization of $2.8 million and $2.2 million at December 31, 2000 and 1999,
respectively.

Stock Based Compensation

Financial Accounting Standards Board ("FASB") SFAS No. 123, "Accounting For
Stock-Based Compensation", prescribes accounting and reporting standards for all
stock-based compensation plans, including employee stock options. As allowed by
SFAS No. 123, the Company has elected to continue to account for its employee
stock-based compensation in accordance with Accounting Principles Board ("APB")
Opinion No. 25, Accounting for Stock Issued to Employees.

Recent Accounting Pronouncements

SFAS No. 133, "Accounting for Derivative Instruments and Hedging Activities", as
amended by SFAS Nos. 137 and 138, establishes standards for recognition and
measurement of derivatives and hedging activities. The adoption of the statement
is required for the Company in the first quarter of fiscal year 2001. The
Company does not believe the adoption of SFAS No. 133 will have a material
financial statement impact.

2.    Marketable Securities

Marketable securities are comprised of the following at December 31, (in
thousands):

<TABLE>
<CAPTION>
                                                                                2000                                 1999
                                                                 -------------------------------------------------------------------
                                                                                Gross                                Gross
                                                                              Unrealized    Fair                  Unrealized   Fair
                                                                     Cost        Gain       Value        Cost       Gain       Value
                                                                 ----------------------------------  -------------------------------
<S>                                                              <C>          <C>          <C>       <C>          <C>        <C>
Common stock.................................................       $2,482      $1,237     $3,719       $2,187      $11,501  $13,688
                                                                 ----------------------------------  -------------------------------
Total marketable securities..................................       $2,482      $1,237     $3,719       $2,187      $11,501  $13,688
                                                                 ==================================  ===============================
</TABLE>

3.    Accounts Receivable

Credit is extended to commercial customers based on an evaluation of their
financial condition, and collateral is not generally required. The evaluation of
financial condition is performed to reduce the risk of loss. The Company has not
experienced any material losses due to uncollectible accounts receivable. The
Company maintains an allowance for doubtful accounts at a level that management
believes is sufficient to cover potential credit losses.

4.    Inventories

Inventories are comprised of the following at December 31, (in thousands):

<TABLE>
<CAPTION>
                                                                                                                 2000       1999
                                                                                                                 ----       ----
  <S>                                                                                                         <C>        <C>
  Raw materials...........................................................................................      $28,727    $16,127
  Work in process.........................................................................................        2,745      3,059
  Finished goods..........................................................................................        9,713      4,115
                                                                                                              ---------------------
                                                                                                                 41,185     23,301
  Obsolescence reserve....................................................................................       (1,781)    (1,529)
                                                                                                              ---------------------
                                                                                                                $39,404    $21,772
                                                                                                              =====================
</TABLE>

                                      F-12
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

5       Property, Plant and Equipment

Property, plant and equipment is comprised of the following (in thousands):

<TABLE>
<CAPTION>
                                                                                    December 31,
                                                                               ------------------------
                                                                                   2000         1999
                                                                                   ----         ----
   <S>                                                                         <C>            <C>
   Land................................................................          $  2,962     $  2,738
   Buildings...........................................................            11,486        9,875
   Machinery and equipment.............................................            87,235       71,141
   Furniture and fixtures..............................................             8,385        7,006
   Leasehold improvements..............................................            10,308        9,486
   Construction in progress............................................            14,350        1,078
                                                                               ------------------------
                                                                                  134,726      101,324
   Accumulated depreciation and amortization...........................           (54,394)     (45,453)
                                                                               ------------------------
                                                                                 $ 80,332     $ 55,871
                                                                               ========================
</TABLE>

Depreciation and amortization expense for property, plant and equipment for the
years ended December 31, 2000, 1999 and 1998 was $11.9 million, $10.6 million
and $9.4 million, respectively.

6       Loans, Notes and Bonds Payable

Loans, notes and bonds payable consist of the following (in thousands):

<TABLE>
<CAPTION>
                                                                                                                      December 31,
                                                                                                                      -----------
                                                                                                                     2000     1999
                                                                                                                     ----     ----
<S>                                                                                                                <C>      <C>
City of Bloomington, Minnesota Industrial Revenue Bond, interest rate is
  variable (4.5% and 4.2% at December 31, 2000 and 1999), quarterly payments
  of $0.1 million, due September 2005..........................................................................    $ 1,900  $ 2,300
Note payable bearing interest at 9.5%, due in three annual installments
  beginning January 1, 1999....................................................................................        889    1,333
Term loans with a Connecticut state agency, bearing interest ranging between
  5%-7.19%, due between January 2000 and June 2005.............................................................      1,324    1,490
Credit lines with commercial banks, bearing interest ranging between
  5.80%-10.00% available through December 2001.................................................................        875    1,508
Notes payable primarily with commercial banks and leasing companies, bearing
  interest ranging between 2.5%-7.0%, due between April 1998 and September
  2008.........................................................................................................      2,190    3,387
Other..........................................................................................................         33       70
                                                                                                                   -----------------
                                                                                                                     7,211   10,088
Less current portion...........................................................................................     (5,101)  (5,601)
                                                                                                                   -----------------
                                                                                                                   $ 2,110  $ 4,487
                                                                                                                   -----------------
</TABLE>

                                      F-13
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

6         Loans, Notes and Bonds Payable (continued)

The balance of loans and notes payable at December 31, 2000 and 1999,
respectively, include amounts due in foreign currencies as follows: Belgian
Francs 47,819,000 and 64,046,000 ($1,117,000 and $1,595,000) and Deutschemarks
2,226,000 and 4,486,000 ($1,073,000 and $2,305,000). The approximate aggregate
debt maturities are as follows as of December 31, 2000 (in thousands):

   2001................................................ $3,601
   2002................................................  1,249
   2003................................................    873
   2004................................................    736
   2005................................................    572
   Thereafter..........................................    180
                                                        ------
                                                        $7,211
                                                        ======

The term loans are collateralized by various equipment, leasehold improvements
and renovations in the Company's Connecticut facility. The majority of the
Company's notes payable are secured by the related real property or equipment.
The Company's credit lines are secured by substantially all the assets of
certain of the Company's subsidiaries and have available borrowing capacity
approximating $1.5 million at December 31, 2000. The Company is in compliance
with the credit line and notes payable covenants.

The bondholders may tender the City of Bloomington, Minnesota bonds at any time
for the principal amount plus accrued interest. As a result, they have been
classified as a current liability. However, for purposes of displaying the
approximate debt maturities above, the bond payments are shown in the years they
are expected to be paid.

Interest paid was $1.2 million, $1.4 million, and $2.3 million, for the years
ended December 31, 2000, 1999, and 1998, respectively.

Certain of the financing agreements of the Company's subsidiaries contain
limitations or prohibitions on the payment of dividends without the lender's
consent or in conjunction with the subsidiary's failure to comply with various
financial covenants. The Company has never declared or paid cash dividends on
its capital stock. The Company does not anticipate paying any cash dividends in
the foreseeable future.

                                      F-14
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

7        Leases

The Company is obligated under capital leases for certain machinery and
equipment that expire at various dates during the next five years. During 2000,
the Company financed approximately $6.8 million of machinery and equipment
through capital lease obligations, which has been treated as a non-cash
transaction for purposes of the Statement of Cash Flows. The gross amount of
machinery and equipment under the capital leases and the related accumulated
depreciation were as follows (in thousands):

<TABLE>
<CAPTION>
                                                                        December 31,
                                                                        ------------
                                                                        2000        1999
                                                                        ----        ----
<S>                                                                   <C>         <C>
Machinery and equipment...........................................    $ 15,107    $  8,267
Leasehold improvements............................................       2,118       2,118
Accumulated depreciation..........................................      (4,520)     (3,178)
                                                                      --------------------
                                                                      $ 12,705     $ 7,207
                                                                      ========     =======
</TABLE>

The following is a schedule of future minimum lease payments for capital leases
as of December 31, 2000 (in thousands):

<TABLE>
   <S>                                                                                  <C>
   2001............................................................................     $ 3,266
   2002............................................................................       2,049
   2003............................................................................       1,676
   2004............................................................................       1,669
   2005............................................................................         417
                                                                                        -------
   Total lease payments............................................................       9,077
   Less amount representing interest...............................................      (1,212)
                                                                                        -------
   Present value of net capital lease payments.....................................       7,865
   Less current portion............................................................      (2,733)
                                                                                        -------
   Long-term portion...............................................................     $ 5,132
                                                                                        =======
</TABLE>

The Company leases office and manufacturing facilities, and certain
manufacturing equipment under several operating leases expiring between 2000 and
2010. Rental expense was $4.9 million, $5.0 million, and $5.2 million, for the
years ended December 31, 2000, 1999 and 1998, respectively.

The following is a schedule of future minimum lease payments for operating
leases as of December 31, 2000 (in thousands):

<TABLE>
<CAPTION>
                                                                                            Operating
                                                                                             Leases
                                                                                             ------
   <S>                                                                                     <C>
   2001...............................................................................      $  4,697
   2002...............................................................................         4,091
   2003...............................................................................         3,091
   2004...............................................................................         2,761
   2005...............................................................................         2,521
   Thereafter.........................................................................         2,909
                                                                                            --------
   Total minimum lease payments.......................................................      $ 20,070
                                                                                            ========
</TABLE>

                                      F-15
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

8.    Income Taxes

Pretax income was taxed in the following jurisdictions (in thousands):

<TABLE>
<CAPTION>
                                                                                                         Year Ended December 31,
                                                                                                       -----------------------------
                                                                                                         2000      1999      1998
<S>                                                                                                    <C>        <C>        <C>
  Domestic.........................................................................................     $64,807   $15,950    $5,331
  Foreign .........................................................................................       5,364     2,594     3,358
                                                                                                        -------   -------    ------
  Total pretax income..............................................................................     $70,171   $18,544    $8,689
                                                                                                        =======   =======    ======
</TABLE>

Significant components of the provision (benefit) for income taxes for the
periods presented are as follows (in thousands):

<TABLE>
<CAPTION>
                                                                                                             December 31,
                                                                                                             ------------
                                                                                                         2000      1999     1998
                                                                                                         ----      ----     ----
  <S>                                                                                                   <C>       <C>       <C>
  Current:
     Federal.......................................................................................     $20,340   $11,811   $4,539
     State.........................................................................................       2,606     1,635    1,116
     Foreign.......................................................................................       2,555       951      648
                                                                                                        -------   -------  -------
  Total current....................................................................................      25,501    14,397    6,303
                                                                                                        -------   -------  -------
  Deferred:
     Federal.......................................................................................         946    (5,901)  (1,816)
     State.........................................................................................         282      (746)    (536)
     Foreign.......................................................................................        (243)      (30)     461
                                                                                                        -------   -------  -------
  Total deferred...................................................................................         985    (6,677)  (1,891)
                                                                                                        -------   -------  -------
                                                                                                        $26,486    $7,720   $4,412
                                                                                                        =======   =======  =======
</TABLE>

Significant components of the Company's deferred tax assets and liabilities are
as follows (in thousands):

<TABLE>
<CAPTION>
                                                                                                                     December 31,
                                                                                                                     ------------
                                                                                                                    2000      1999
                                                                                                                    ----      ----
<S>                                                                                                                <C>       <C>
Deferred tax assets:
Accrued liabilities..........................................................................................       $2,403   $3,565
Inventory adjustments........................................................................................        2,150    1,713
Net operating loss and tax credit carryforwards..............................................................        1,584    1,823
Other, net...................................................................................................        1,129      266
                                                                                                                    ------  -------
                                                                                                                     7,266    7,367
Valuation allowance..........................................................................................         (317)       -
                                                                                                                    ---------------
                                                                                                                     6,949    7,367
Deferred tax liabilities:
Depreciation and amortization................................................................................       (4,199)  (3,736)
Unrealized gain on marketable securities.....................................................................         (489)  (4,141)
Other, net...................................................................................................          (11)    (313)
                                                                                                                   -------  -------
                                                                                                                    (4,699)  (8,190)
                                                                                                                   -------  -------
Net deferred tax assets (liabilities)........................................................................      $ 2,250  $  (823)
                                                                                                                   =======  =======
</TABLE>

The valuation allowance relates to realizability of net operating losses of
foreign entities.

                                      F-16
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

8.    Income Taxes (continued)

As of December 31, 2000, the Company has federal net operating loss
carryforwards of $2.0 million attributable to certain acquired companies. The
net operating loss and tax credit carryforwards will expire at various dates in
2009 through 2018, if not utilized. Utilization of the net operating losses and
credits may be subject to a substantial annual limitation due to the "change in
ownership" provisions of the Internal Revenue Code of 1986 and similar state
provisions.

Income taxes paid for the years ended December 31, 2000, 1999, and 1998 were
$20.5 million, $9.2 million and $9.4 million, respectively.

The reconciliation of income tax computed at the U.S. federal statutory tax rate
to the Company's tax expense is (in thousands):

<TABLE>
<CAPTION>
                                                                                                   For the Year Ended December 31,
                                                                                                   -------------------------------
                                                                                                      2000      1999      1998
                                                                                                      ----      ----      ----
<S>                                                                                                <C>         <C>        <C>
U.S. statutory rate..........................................................................       $ 24,559   $ 6,489    $2,957
State income taxes...........................................................................          1,831       657       266
Foreign income taxes.........................................................................             43      (162)      228
Effect of nondeductible acquisition expenses.................................................            525     1,851       599
Foreign sales corporation benefit............................................................         (1,737)     (773)     (324)
Change in valuation allowance of deferred tax assets.........................................            317    (2,154)      855
Tax liabilities accrued......................................................................            506     1,511        --
Other, net...................................................................................            442       301      (169)
                                                                                                    --------   -------    ------
                                                                                                    $ 26,486   $ 7,720    $4,412
                                                                                                    ========   =======    ======
</TABLE>

The former securityholders of the ADCS Group have agreed to indemnify the
Company against losses arising out of certain tax matters. As security for these
tax matters, the former securityholders of the ADCS Group have delivered 700,000
shares of the Company's common stock which they received into escrow. While the
possible exposures are difficult to quantify, the Company believes that,
regardless of the probability that liabilities arise, the potential exposures
range from $0 to $22 million depending on the tax matter. Although the former
securityholders of the ADCS Group have agreed to indemnify the Company against
losses arising out of such tax matters, any assessments, if ultimately
determined against the Company, would result in a charge to the Company's
results of operations. During the second quarter of 1999, the Company was
notified by the Internal Revenue Service of an assessment of $2.1 million for
certain tax matters. The Company intends to vigorously defend its position in
these tax matters.

                                      F-17
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

9.   Profit Sharing Plan

The Company maintains a 401(k) profit sharing plan covering substantially all of
its domestic employees and is subject to the provisions of the Employee
Retirement Income Security Act of 1974. The Company's matching contributions are
discretionary by plan year and were $0.6 million, $0.4 million and $0.1 million
for 2000, 1999 and 1998, respectively.

10.  Stockholders' quity

On April 4, 2000, the Company completed a registered underwritten public
offering of 2,800,000 shares of the Company's common stock. Of such shares, the
Company sold 1,500,000 shares and certain stockholders sold 1,300,000 shares.
The Company received net proceeds from the offering of approximately $63.4
million. The cost of the offering was approximately $4.1 million.

In March 1998, the Company completed a registered underwritten public offering
of 5,428,000 shares, including over-allotments, of common stock. Net proceeds to
the Company of $62.4 million were from 2,257,291 shares sold by the Company
while 3,170,709 shares were sold by certain stockholders. Costs of the offering,
including underwriting commissions, were $4.2 million.

Stock Plans

The Company has certain stock plans, which provide for the granting of up to
6,515,833 nonqualified stock options, incentive stock options ("ISOs"), stock
appreciation rights and restricted stock awards to employees, directors and
consultants of the Company.

Under the terms of these stock plans, nonqualified options granted may not be at
a price of less than 50% of the fair market value of the common stock on the
date of grant, and ISOs granted may not be at a price of less than 100% of fair
market value of the common stock on the date of grant. All grants have been made
at fair market value under the plans. Options are generally exercisable
commencing one year after the date of grant at the rate of 20% per annum on a
cumulative basis. Nonqualified options expire up to ten years from the date of
grant, and ISOs expire five to ten years from the date of grant.

<TABLE>
<CAPTION>
                                                                                                         Number of     Option Price
                                                                                                           Shares        Per Share
                                                                                                           ------        ---------
  <S>                                                                                                    <C>           <C>
  Options outstanding at December 31, 1997.......................................................         1,550,952  $ 0.28 - $29.38
    Granted......................................................................................           752,440  $14.00 - $33.00
    Canceled.....................................................................................          (110,130) $ 5.63 - $33.00
    Exercised....................................................................................          (158,918) $ 0.28 - $17.63
                                                                                                         ----------  ---------------
  Options outstanding at December 31, 1998.......................................................         2,034,344  $ 0.28 - $33.00
    Granted......................................................................................         1,148,954  $19.19 - $37.38
    Canceled.....................................................................................          (134,658) $ 5.63 - $27.00
    Exercised....................................................................................          (204,085) $ 0.28 - $29.38
                                                                                                         ----------  ---------------
  Options outstanding at December 31, 1999.......................................................         2,844,555  $ 0.44 - $37.38
    Granted......................................................................................         1,524,665  $15.31 - $60.00
    Canceled.....................................................................................          (440,411) $ 8.09 - $60.00
    Exercised....................................................................................          (496,711) $ 0.44 - $30.50
                                                                                                         ----------  ---------------
  Options outstanding at December 31, 2000.......................................................         3,432,098  $ 0.53 - $60.00
                                                                                                         ==========  ===============
</TABLE>

At December 31, 2000, options for 956,060 shares were exercisable and options
for 1,722,913 shares were available for grant. Exercise prices for 406,309
options outstanding ranged from $0.53-$12.00; 328,650 options outstanding ranged
from $12.01-$18.00; 539,631 options outstanding ranged from $18.01-$24.00;
1,716,048 options outstanding ranged from $24.01-$36.00; 426,110 options
outstanding ranged from $36.01-$48.00; and 15,350 options outstanding ranged
from $48.01-$60.00 as of December 31, 2000.

                                      F-18
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

10.  Stockholders' Equity (continued)

The weighted average exercise price and remaining contractual life of options
outstanding at December 31, 2000 was $25.35 and 7.8 years, respectively.

As a result of the NOW and MST mergers in 1998 and 1999, respectively (see Note
11), stock options of NOW and MST were converted into 205,089 and 123,016 of
ATMI stock options. NOW stock options were converted into ATMI stock options at
historical prices ranging from $4.04 to $8.90 and MST stock options were
converted into ATMI stock options at historical prices ranging from $2.10 to
$15.74.

If compensation expense for the Company's plans had been determined for all
stock option grants based on the fair value at the grant dates for awards under
those plans, consistent with the method described in SFAS No. 123, the Company's
net income, net income per share-basic and net income per share-assuming
dilution would have been reduced to the pro forma amounts indicated below (in
thousands, except per share data):

<TABLE>
<CAPTION>
                                                                                                                Pro forma
                                                                                                                ---------
                                                                                                        2000       1999      1998
                                                                                                        ----       ----      ----
<S>                                                                                                     <C>        <C>       <C>
Net income........................................................................................      $34,653    $7,226    $2,326
Net income per share--basic........................................................................     $  1.20    $ 0.27    $ 0.09
Net income per share--assuming dilution...........................................................      $  1.14    $ 0.25    $ 0.08
</TABLE>

The fair value of each option grant, for pro forma disclosure purposes, was
estimated on the date of grant using the Black-Scholes option-pricing model with
the following weighted average assumptions:

<TABLE>
<CAPTION>
                                                                                                      2000        1999      1998
                                                                                                      ----        ----      ----
<S>                                                                                                 <C>        <C>        <C>
Expected dividend yield.........................................................................         None       None       None
Risk free interest rate.........................................................................          6.0%      5.80%      5.50%
Expected volatility.............................................................................         .615       .615       .628
Expected life of options........................................................................    6.5 years  7.5 years  7.5 years
</TABLE>

The weighted average fair value of non-canceled stock options granted in 2000,
1999 and 1998 was $21.29, $17.18 and $14.74, respectively.

Option valuation models require the input of highly subjective assumptions,
including the expected stock price volatility. Because changes in the subjective
assumptions can materially affect the fair value estimate, in the opinion of
management, the existing models do not necessarily provide a reliable single
measure of the fair value of the Company's employee stock options.

Employee Stock Purchase Plan

The Employee Stock Purchase Plan ("ESPP Plan") was approved in May 1998
authorizing 500,000 shares for subscription and enabling all employees to
subscribe at six-month intervals to purchase shares of common stock at the lower
of 85% of the fair market value of the shares on the first day or last day of
each six-month period. At December 31, 2000, 381,000 shares remain available
under the ESPP Plan.

                                      F-19
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

10.   Stockholders' Equity (continued)

    Earnings Per Share

    The following table presents the computation of basic and diluted earnings
per share (in thousands, except per share data):

<TABLE>
<CAPTION>
                                                                                                     2000          1999         1998
                                                                                                     ----          ----         ----
<S>                                                                                               <C>          <C>            <C>
Numerator:
     Net income........................................................................           $43,685      $10,824        $4,277
                                                                                                  =======      ========       ======
Denominator:
            Denominator for basic earnings per share-
                Weighted-average shares................................................            28,928        26,773       25,978
            Dilutive effect of contingent shares related to
                acquisitions subject to escrow arrangements............................               737         1,186        1,326
            Dilutive effect of employee stock options...................................              625           730          489
                                                                                                      ---           ---          ---
            Denominator for diluted earnings per share.................................            30,290        28,689       27,793
                                                                                                   ======      ========       ======

Net income per share--basic............................................................           $  1.51      $   0.40       $ 0.16
                                                                                                  =======      ========       ======

Net income per share--assuming dilution................................................           $ 1. 44      $   0.38       $ 0.15
                                                                                                  =======      ========       ======
</TABLE>

Options to purchase 723,580, 18,900 and 720,520 shares of common stock,
outstanding as of December 31, 2000, 1999 and 1998, respectively, were not
included in the computation of diluted earnings per share because their exercise
prices were greater than the average market price of the common shares and,
therefore, their inclusion would be antidilutive.

11.  Mergers and Acquisitions

The Company has consummated seven mergers in the three years ended December 31,
2000, each of which has been accounted for as a pooling of interests. The
entities acquired and share consideration exchanged were as follows:

<TABLE>
<CAPTION>
                                                                                                                    Shares Held in
                                                                                     Year of                            Escrow
Company                                                                            Acquisition     Shares Issued  December 31, 2000
-------                                                                            -----------     -------------  -----------------
<S>                                                                                <C>             <C>            <C>
Environmentally Safe Cleaning Alternatives, Inc.                                      2000               370,000              37,000
TeloSense Corporation                                                                 1999               232,000                   -
Advanced Chemical Systems International, Inc.                                         1999             1,202,000                   -
Delatech Incorporated                                                                 1999             2,347,000                   -
Newform N.V.                                                                          1999               550,000                   -
MST Analytics, Inc.                                                                   1999               993,000                   -
NOW Technologies, Inc.                                                                1998             1,594,000                   -
</TABLE>

                                      F-20
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

11.  Mergers and Acquisitions (continued)

The former securityholders of the aforementioned entities have agreed to
indemnify the Company from and against certain losses arising out of breaches of
representations and warranties made by the respective securityholders. As
security for these obligations, certain former securityholders agreed to escrow
a certain specified amount of the merger consideration. Certain of these shares
have been, and will continue to be, released from escrow in accordance with the
terms of the respective merger agreements.

The Company has reduced retained earnings by $95,000, $163,000 and $102,000 in
2000, 1999 and 1998, respectively, to adjust retained earnings for the different
fiscal year ends of certain of the acquired entities and has combined the
year-end September 30, 1999 and 1998 financial results for ESCA with the
December 31, 1999 and 1998 financial results of the Company.

In connection with the investigation, analysis and closings of the
aforementioned transactions, the Company recorded merger costs and related
expenses of $1.5 million, $10.5 million and $1.7 million in 2000, 1999, and
1998, respectively. During 1999, the Company reversed approximately $0.6 million
of merger costs accrued in prior years. Included within merger costs and related
expenses in 1999 is a charge of $4.4 million related to the Delatech acquisition
to recognize the impaired value of certain inventory ($1 million) and goodwill
($3.4 million) associated with an existing environmental equipment product line.

For the years ended December 31, 2000, 1999 and 1998, prior to the acquisitions,
revenues and net income of acquired companies included in the financial
statements are as follows (in thousands):

<TABLE>
<CAPTION>
Revenues:                                                                                 2000          1999           1998
-------                                                                              -------------------------------------------
<S>                                                                                  <C>                 <C>           <C>
ATMI...........................................................................             $296,383      $196,236      $ 97,874
ESCA...........................................................................                3,577         6,270         2,955
TeloSense, ACSI and Delatech...................................................                    -             -        42,994
Newform and MST................................................................                    -             -        24,238
                                                                                     --------------------------------------------
   Consolidated revenues.......................................................             $299,960      $202,506      $168,061
                                                                                     ============================================
                                                                                     --------------------------------------------
Net Income (Loss):                                                                        2000          1999           1998
------------------                                                                   -------------------------------------------
<S>                                                                                  <C>                  <C>          <C>
ATMI...........................................................................              $43,563       $10,546       $ 6,465
ESCA...........................................................................                  122           278          (658)
TeloSense, ACSI and Delatech...................................................                    -             -        (2,024)
Newform and MST................................................................                    -             -           494
                                                                                     --------------------------------------------
   Consolidated net income.....................................................              $43,685       $10,824       $ 4,277
                                                                                     ============================================
</TABLE>

On December 28, 2000, ATMI purchased K.C. Tech Co., Ltd.'s 30% interest in the
operations of ADCS-Korea for approximately $7.2 million, of which $5.0 million
was paid in 2000. The operations of ADCS-Korea have historically been included
in the consolidated statements of income of ATMI. The 30% portion not
historically owned by ATMI had been accounted for as minority interest. The
transaction was accounted for as a purchase and the excess cost over fair value
of the net assets acquired is being amortized on a straight-line basis over a
twenty-year period.

                                      F-21
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)


12.  Other Comprehensive Income

SFAS No. 130, "Reporting Comprehensive Income", requires the reporting of
comprehensive income in addition to net income from operations. Comprehensive
income is a more inclusive financial reporting methodology that includes
disclosure of certain financial information that historically has not been
recognized in the calculation of net income.

The components of other comprehensive income are as follows (in thousands):

<TABLE>
<CAPTION>
                                                                          Currency           Unrealized Gain
                                                                        Translation        (Loss) on Available-
                                                                        Adjustments        for-Sale Securities          Total
                                                                    -----------------------------------------------------------
<S>                                                                 <C>                    <C>                        <C>
Balance at December 31, 1997...................................          $ (1,454)                 $  --               $ (1,454)

Unrealized loss on available-for-sale
  securities (net of tax benefit of $281)......................                --                   (500)                  (500)
Cumulative translation adjustment..............................               801                     --                    801
                                                                    -----------------------------------------------------------
Balance at December 31, 1998...................................              (653)                  (500)                (1,153)
                                                                    -----------------------------------------------------------
Unrealized gain on available-for-sale
  securities (net of tax provision of $4,141)..................                --                  7,860                  7,860
Cumulative translation adjustment..............................              (201)                    --                   (201)
                                                                    -----------------------------------------------------------
Balance at December 31, 1999...................................              (854)                 7,360                 (6,506)
                                                                    -----------------------------------------------------------
Reclassification adjustment for realized gain on
  available-for-sale securities sold (net of tax provision of
  $2,161)........................................................                                 (3,680)                (3,680)
Unrealized loss on available-for-sale
  securities (net of tax benefit of $1,618)....................                --                 (2,895)                (2,895)
Cumulative translation adjustment..............................            (1,026)                    --                 (1,026)
                                                                    -----------------------------------------------------------
Balance at December 31, 2000...................................          $ (1,880)                 $ 785               $ (1,095)
                                                                    ===========================================================
</TABLE>

13. Severance Charge

During the fourth quarter of 1999, the Company terminated the employment of four
executive officers within its Materials segment and one executive officer within
its Technologies segment and recorded a charge of $2.3 million, reflected in
selling, general, and administrative expenses in the Company's 1999 results of
operations. As of December 31, 2000, $20 million of the severance charge has
been paid, with a balance of $0.3 million remaining in the accrual at this date.
This remaining amount was subsequently paid in the first quarter of 2001.

                                      F-22
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

14.  Commitments and Contingencies

In July 1999, ATMI filed suit against a Company, alleging infringement of
certain liquid delivery system patents. Later in 1999, that Company filed suit
against ATMI alleging infringement of a particular semiconductor process patent.
In January 2001, a letter of intent was executed that addressed the settlement
of both claims. Details of the settlement are currently being finalized, the
terms of which will have no material adverse effect on ATMI.

In the normal course of business, the Company is involved in various lawsuits
and claims. Although the ultimate outcome of any of these legal proceedings
cannot be determined at this time, management, including internal counsel, does
not believe that the outcome of these proceedings, individually or in the
aggregate, will have a material adverse effect on the Company's financial
position or results of operations.

15.  Segment and Geographic Data

As defined by SFAS No. 131, "Disclosure About Segments of an Enterprise and
Related Information" the Company has two reportable operating segments:
Materials and Technologies. The reportable operating segments are each managed
separately because they manufacture and distribute distinct products with
different production processes. The Company evaluates performance and allocates
resources based on operating profit or loss, excluding merger costs and related
expenses, interest, other income or expense, and income taxes. Intercompany
sales are not material among segments or operating divisions. The general
corporate assets primarily include cash, cash equivalents, marketable
securities, goodwill and other long-lived assets.

The following tables provide reported financial information for each of these
reportable segments (in thousands):

                                          For the year ended December 31,
                                          -------------------------------
                                          2000           1999          1998
                                         ------------------------------------

Revenues
--------
Materials..............................  $138,191      $ 96,711      $ 71,279
Technologies...........................   161,769       105,795        96,782
                                         ------------------------------------

Consolidated revenues..................  $299,960      $202,506      $168,061
                                         ====================================

Operating Income
----------------
Materials..............................  $ 36,655      $ 19,335      $ 11,373
Technologies...........................    20,455         5,536        (3,899)
Merger costs and related expenses......    (1,500)       (9,914)       (1,700)
                                         ------------------------------------

Consolidated operating income..........  $ 55,610      $ 14,957      $  5,774
                                         ====================================

                                      F-23
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

15.  Segment and Geographic Data (continued)

                                           For the year ended December 31,
                                           -------------------------------
                                           2000          1999          1998
Capital Expenditures
--------------------
Materials........................        $  8,489     $  4,198      $  5,141
Technologies.....................          15,909        3,611         7,260
Corporate........................           5,122        2,907         3,300
                                    -------------- ------------ -------------

Total Capital Expenditures.......        $ 29,520     $ 10,716      $ 15,701
                                    ============== ============ =============

Identifiable Assets
-------------------
Materials........................        $ 74,194     $ 60,717
Technologies.....................         130,838       81,466
General corporate assets.........         145,773       86,666
                                    -------------- ------------

Total consolidated assets........        $350,805     $228,849
                                    ============== ============


The Company's geographic data for the years ended December 31, 2000, 1999 and
1998 are as follows:

<TABLE>
<CAPTION>
(In thousands)                                                                 Other        Europe and
--------------                              United States      Taiwan       Pacific Rim       Other       Eliminations     Total
                                            ------------- --------------- -------------- --------------- -------------- ------------
<S>                                         <C>           <C>             <C>            <C>             <C>            <C>
December 31, 2000
  Total revenues                                $173,208         $38,716        $54,108         $41,920       $(7,992)    $299,960
  Long-lived assets                               82,617             322          1,368           6,000             -       90,307

December 31, 1999
  Total revenues                                 125,506          22,825         31,738          24,176        (1,739)     202,506
  Long-lived assets                               57,724               -          1,589             638             -       59,951

December 31, 1998
  Total revenues                                 115,415           6,875         27,576          20,779        (2,584)     168,061
  Long-lived assets                               61,817               -          1,373             653             -       63,843
</TABLE>

Revenues are attributed to countries based on the location of the customer.
Other than Taiwan, no one specific country within the Pacific Rim or within
Europe accounted for greater than 10% of consolidated revenues in 2000, 1999 and
1998. Revenues and net income of the foreign subsidiaries are not material to
the consolidated operations of the Company for each of the three years in the
period ended December 31, 2000.


16.  Event (unaudited) Subsequent to the Date of the Report of Independent
     Auditors

On February 7, 2001, in response to softening industry conditions and the
Company's intent to more aggressively integrate previous acquisitions and reduce
costs of infrastructure, a restructuring initiative was announced. The Company
will take a pre-tax charge of approximately $9.0 million, which will be
recognized in the first quarter of 2001, to reflect this initiative, comprised
of the following: involuntary employee termination benefits; write-offs due to
asset impairments; and facility exit costs, including early lease termination
fees. This charge is anticipated to be funded with operating cash flows. The
project initiative will be carried out over twelve months and includes certain
facility closures and the related relocation of production assets, a reduction
in workforce in administrative, operational, and sales functions and the
outsourcing of non-core activities, as well as asset impairments related to
those initiatives. These actions are expected to result in a net employment
reduction of approximately 10% of the workforce.

                                      F-24
<PAGE>

                                  ATMI, INC.

            NOTES TO CONSOLIDATED FINANCIAL STATEMENTS--(Continued)

                  Quarterly Results of Operations (unaudited)
                   (In thousands, except per share amounts)

<TABLE>
<CAPTION>
                                                                                    Quarter
                                                        ----------------------------------------------------------------

2000                                                            First           Second           Third          Fourth
----                                                            -----           ------           -----          ------
<S>                                                             <C>             <C>              <C>            <C>
Revenues............................................            $63,027         $71,142          $78,948        $86,843
Gross profit........................................             33,298          37,954           41,974         44,023
Net income..........................................             13,638 (a)       9,769            9,651 (b)     10,627
Net income per share--basic.........................            $  0.49         $  0.33          $  0.33        $  0.36
Net income per share--assuming
    dilution.......................................             $  0.46         $  0.31          $  0.32        $  0.35

                                                                                    Quarter
                                                        ----------------------------------------------------------------

1999                                                            First           Second           Third          Fourth
----                                                            -----           ------           -----          ------

Revenues...........................................             $38,517         $50,947          $53,677        $59,365
Gross profit.......................................              19,851          27,310           28,130         31,759
Net income (loss)..................................               1,744            (577) (c)       5,988          3,669 (d)
Net income (loss) per share--basic.................             $  0.06         $ (0.02)         $  0.22        $  0.14
Net income (loss) per share--assuming
    dilution.......................................             $  0.06         $ (0.02)         $  0.21        $  0.13
</TABLE>

     (a)  Includes $9.5 million gain on sale of certain marketable securities in
          the first quarter of 2000, offset by a loss of $1.3 million in the
          same quarter on certain other investments.

     (b)  Includes merger costs and related expenses of $1.5 million incurred
          in the ESCA acquisition.

     (c)  Includes merger costs and related expenses of $7.2 million incurred in
          the ACSI, Delatech, and TeloSense acquisitions.

     (d)  Includes merger costs and related expenses of $3.3 million incurred in
          completing the MST Analytics and Newform N.V. acquisitions, and a
          charge of $2.3 million of severance for five executive officers.

                                      F-25
<PAGE>

                                  Schedule II

                                  ATMI, INC.
                       VALUATION AND QUALIFYING ACCOUNTS
                                (In thousands)

<TABLE>
<CAPTION>
                                                                       Balance at                                       Balance at
                                                                       Beginning        Charged to                          End
Year Ended                                                             of Period       Cost/Expense      Deductions      of Period
----------                                                             ---------       ------------      ----------      ---------
<S>                                                                    <C>             <C>               <C>             <C>
December 31, 2000
    Allowance for doubtful accounts............................            $1,366           $  431         $   (72) (a)   $  1,725
    Obsolescence reserve.......................................             1,529              733            (481) (b)      1,781
    Severance accrual..........................................             2,300                0          (1,991) (c)        309

December 31, 1999
    Allowance for doubtful accounts............................               959              587            (180) (a)      1,366
    Obsolescence reserve.......................................             1,861            1,143          (1,475) (b)      1,529
    Severance accrual..........................................                 0            2,300               0           2,300

December 31, 1998
    Allowance for doubtful accounts.............................            1,487              399            (927) (a)        959
    Obsolescence reserve.......................................             1,737            1,365          (1,241) (b)      1,861
    Severance accrual...........................................                0              402            (402) (c)          0
</TABLE>

(a)  Reflects write offs of bad debts.

(b)  Reflects disposals of obsolete inventory.

(c)  Reflects payments made during the current year.

                                      F-26