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                                                                   Exhibit 10.03

                             EMPLOYMENT AGREEMENT



                                April 26, 2000



Douglas A. Neugold
125 Lake Ridge Road
Southbury, CT 06844


     Advanced Technology Materials, Inc., a Delaware corporation, has agreed to
enter into an employment agreement with you. The "Company" as used in this
Agreement shall be defined as Advanced Technology Materials, Inc., and for
purposes of Section 7 hereof shall include any of its subsidiaries or affiliates
for which you provide any product, process, technology or service to or
supervise or otherwise participate in during the two (2) years prior to the
termination of your employment with Advanced Technology Materials, Inc. You have
agreed to enter into an employment agreement containing, among other things,
restrictions on your ability to compete with the business of the Company and its
subsidiaries and affiliates to the extent provided in the preceding sentence for
a period of time following your termination of employment.

     Accordingly, in consideration of the premises and the mutual promises and
covenants contained herein and for other good and valuable consideration,
including but not limited to (i) your receipt of a term of employment pursuant
to Section 2 of this Agreement; (ii) your access to and receipt of the
confidential, proprietary and trade secret information of the Company and its
subsidiaries and affiliates; (iii) your receipt of compensation pursuant to
Section 3 of this Agreement; (iv) your receipt of other benefits pursuant to
Section 4 of this Agreement; (v) your receipt of a stock grant of common date
herewith; and (vi) your revised job description and responsibilities, the
receipt and sufficiency of which are hereby expressly acknowledged, effective
the date of this Agreement, the Company and you agree as follows:

     1.   Position and Responsibilities.
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     1.1  You shall serve as President of the Company, or in such other capacity
as shall be designated by the Board of Directors of ATMI, Inc. ("ATMI"). You
shall perform such duties at Danbury, Connecticut or such other place as you and
the Company shall mutually agree.

     1.2  You will, to the best of your ability, devote your full time and best
efforts to the performance of your duties hereunder and to the business and
affairs of the Company. You agree to serve as an officer of the Company and/or
ATMI, if elected by their respective Board of Directors, and to perform such
executive duties as may be assigned to you by their respective Board of
Directors from time to time.

     1.3  You will duly, punctually and faithfully perform and observe any and
all rules and regulations which the Company and/or ATMI may now or shall
hereafter establish governing the conduct of the Company's business.

     2.   Term of Employment.
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     2.1  The term of your employment shall be two (2) years (the "Initial
Term") commencing with the date hereof, provided your employment shall
automatically terminate upon your death and may be terminated at any time as
provided in Section 2.2. At the end of the Initial Term, unless the parties
mutually agree to renew, extend or modify the provisions hereof, your employment
shall continue "at will," subject to the Company's obligation to pay the
Severance Payment as hereinafter provided, and the other terms and conditions of
this Agreement (as then in effect) shall continue.

     2.2  The Company shall have the right, on written notice to you specifying
the reason, to terminate your employment:

     (a)  immediately for Cause (as defined in Section 2.4), or

     (b)  subject to Section 2.6 hereof, at any time without Cause, or
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     (c)  in the event of your total disability which, in the reasonable opinion
of the Board of Directors of ATMI, renders you unable or incompetent to carry
out your duties, responsibilities, and assignments for a period of ninety (90)
consecutive days.

     2.3  You shall have the right, on written notice to the Company, to
terminate your employment if you "resign for just cause," which shall mean a
resignation of your employment as a direct result of (a) a material breach by
the Company of its obligations to you under this Agreement, provided that, if
such breach is capable of remedy, a written notice within sixty (60) days of
such breach and opportunity to cure such breach shall be afforded the Company
and, in such event, just cause shall exist if the Company shall fail to cure
such breach within a reasonable period of time not to exceed thirty (30) days;
or (b) a significant decrease by the Board of Directors of ATMI of your duties
or authority (except in connection with a termination pursuant to Section 2.2(a)
or (c)), provided that you have given the Company notice of such decrease within
three (3) months of its occurrence.

     2.4  The term "Cause" shall mean (i) your failure or refusal to render
substantial services to the Company in accordance with your obligations under
this Agreement, provided that if your failure or refusal is capable of remedy, a
written notice within three (3) months of such failure or refusal and
opportunity to cure shall be afforded you and, in such event, Cause shall exist
if you fail to cure such failure or refusal within a reasonable period of time
not to exceed thirty (30) days or if such failure or refusal is timely cured,
you repeat such failure or refusal; (ii) the commission by you of an act of
fraud or embezzlement against the Company or the commission by you of any other
action with the intent to injure the Company; (iii) an act of moral turpitude by
you which is materially detrimental to the business or reputation of the
Company; or (iv) your having been convicted of, or pleading nolo contendere to,
a felony (other than traffic offenses which do not bring you or the Company into
disgrace or disrepute). For purposes of this Section 2.4, the term "Company"
shall include the Company and its subsidiaries and affiliates.

     2.5  If you are terminated for Cause, neither the Company nor any affiliate
of the Company shall have any further obligation to you or your personal
representatives under this Agreement, except for salary, additional compensation
and permitted business expenses accrued hereunder and unpaid at the date of
termination. On or before the date of termination of your employment, you shall
return to the Company all records and other personal property of the Company in
your possession or control, including all confidential, proprietary or trade
secret information of the Company and its subsidiaries and affiliates.

     2.6  In the event of the termination of your employment pursuant to either
Section 2.2(b) or Section 2.3, the Company shall pay to you an aggregate of
twelve (12) months' Base Salary at the time of termination, less applicable
taxes and withholding (the "Severance Payment"), in the manner and subject to
the terms and conditions as hereinafter provided, and the Company shall provide
you during such period medical, dental, life and disability insurance benefits
on the same basis the Company would have provided you such benefits during such
period had you continued to be an employee of the Company (collectively, the
"Severance Benefits"). The Severance Payment shall be payable in installments on
such date or dates on which Base Salary would have been paid to you had your
employment not been terminated.

     2.7  In the event of the termination of your employment associated with a
"change in control" of ATMI (including if you "resign for just cause" as defined
in Section 2.3), (a) all stock options held by you to purchase shares of ATMI
Common Stock shall become immediately exercisable, notwithstanding the vesting
provisions of any stock option award agreement concerning such options; provided
that such acceleration of vesting shall not occur if and to the extent that (i)
ATMI's independent accountant has advised the Board of Directors of ATMI that
such acceleration could prohibit the accounting treatment of the transaction
which is a change in control as a pooling of interests under Accounting
Principles Board Opinion No. 16 (or any successor opinion) and (ii) the Board of
Directors of ATMI intends to treat such transaction as a pooling of interests,
in which case options would continue to vest as permitted within the terms of
the applicable stock plans and stock option award agreements; and (b) you will
be entitled to any bonuses under any bonus plans then in effect as if fully
earned. Benefits payable under this Section 2.7 upon a change in control may
subject you to an excise tax as "excess parachute payments" under Section 280G
of the Internal Revenue Code. ATMI will reimburse you for all excise taxes paid,
but the reimbursement will constitute an excess parachute payment and will be
subject to further excise tax. Such further excise tax will trigger further
reimbursement by ATMI. For purposes of this Section 2.7, a "change in control"
of ATMI shall be deemed to have taken place if: (i) a third person, including a
"person" as defined in Section 13(d)(3) of the Securities and Exchange Act
becomes the beneficial owner (as defined in Rule 13d-3 under the Securities and
Exchange Act) directly or indirectly, of securities of ATMI representing twenty-
five percent (25%) or more of the total number of votes that may be cast for the
election of the directors of ATMI; or (ii) as the result of, or in connection
with, any tender or exchange offer, merger, consolidation or other business
combination, sale of assets or one or more contested elections, or any
combination of the foregoing transactions (a "Transaction"), the persons who
were directors of ATMI immediately prior to the Transaction shall cease to
constitute a majority of the Board of Directors of ATMI or of any successor to
ATMI.

     3.   Compensation.
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     3.1  The Company shall pay to you for the services to be rendered hereunder
a Base Salary ("Base Salary") at an annual rate of $280,000, subject to
customary withholding for federal, state and local taxes. Such Base Salary shall
be payable periodically in conformity with the prevailing practice of ATMI and

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ATMI's subsidiaries for executives' compensation as such practice shall be
established or modified from time to time. Such Base Salary shall be subject to
increase from time to time to take into account appropriate cost of living
adjustments and general compensation increases based on performance, in the
discretion of the Board of Directors of ATMI.

     3.2  You shall be entitled to be reimbursed for all reasonable and
necessary expenses incurred in connection with the performance of your duties
hereunder provided that you shall, as a condition of reimbursement, submit
verification of the nature and amount of such expenses in accordance with the
reimbursement policy from time to time adopted by the Company and/or ATMI.

     4.   Other Benefits.
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     4.1  You shall be entitled to vacation in accordance with the vacation
policy of ATMI and ATMI's subsidiaries, as the same may be in effect from time
to time, without loss of compensation or other benefits to which you are
entitled under this Agreement, to be taken at such times as you may reasonably
select.

     4.2  The Company will provide to you all other employee benefits generally
available to employees of ATMI and ATMI's subsidiaries of equivalent position,
as the same may be in effect from time to time.

     4.3  You shall be eligible to receive additional compensation, including
awards of performance bonuses at levels commensurate with employees of ATMI and
ATMI's subsidiaries of equivalent position and grants of employee stock options,
in each case in the discretion of the Compensation Committee of the Board of
Directors of ATMI. Additional incentive compensation may be earned pursuant to
the conditions of the annual letter reflecting your "MBO" goals, typically sent
on or about January 1st of the applicable year, or on a later date pursuant to
any change in your responsibilities.

     5.   Other Activities During Employment.
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     5.1  Except with the prior written consent of the ATMI's Board of
Directors, which consent shall not be unreasonably withheld, you will not during
the term of this Agreement undertake or engage in any other employment or
occupation except as permitted by Section 5.3. This provision shall not be
deemed to preclude membership in professional societies, lecturing or the
acceptance of honorary positions, that are in any case incidental to your
employment by the Company, which are not adverse or antagonistic to or
competitive with the Company or its subsidiaries or affiliates, their business
or prospects, financial or otherwise and are consistent with your obligations
regarding the confidential, proprietary and trade secret information of the
Company and its subsidiaries and affiliates.

     5.2  Except as permitted by Section 5.3, you will not assume or participate
in, directly or indirectly, any position or interest adverse or antagonistic to
the Company or its subsidiaries or affiliates, their business or prospects,
financial or otherwise, or take any action towards any of the foregoing.

     5.3  During the term of your employment by the Company, except on behalf of
the Company or its subsidiaries or its affiliates, you will not, directly or
indirectly, whether as an officer, director, stockholder, partner, proprietor,
associate, representative or otherwise, become or be interested in any other
person, corporation, firm, partnership or other entity whatsoever which directly
competes with the Company or its subsidiaries or affiliates, in any part of the
world, in any line of business engaged in (or planned to be engaged in) by the
Company or its subsidiaries or affiliates (or any successor to their business).
With respect to any company or partnership which directly competes with the
Company or its subsidiaries or affiliates, in any part of the world, in any line
of business engaged in (or planned to be engaged in) by the Company or its
subsidiaries or affiliates (or any successor to their business), this Section
5.3 shall not prohibit you from owning (i) as a passive investor only, an
aggregate of not more than one percent (1%) of the total stock or equity
interests of such company or partnership if the same are publicly traded, or
(ii) stock or equity interests of such company or partnership through mutual
funds or other similar investment vehicles over which you retain no investment
discretion.

     6.   Former Employment.
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     6.1  You represent and warrant that your employment by the Company will not
conflict with and will not be constrained by any prior employment or consulting
agreement or relationship. Subject to Section 6.2, you represent and warrant
that you do not possess confidential information arising out of prior employment
(other than with the Company) which, in your best judgment, would be utilized in
connection with your employment by the Company in the absence of Section 6.2.

     6.2  If, in spite of the second sentence of Section 6.l, you should find
that confidential information belonging to any former employer might be usable
in connection with the Company's business, you will not intentionally disclose
to the Company or use on its behalf any confidential information belonging to
any of your former employers; but during your employment by the Company, you
will use in the performance of your duties all information which is generally
known and used by persons with training and experience comparable to your own
and all information which is common knowledge in the industry or otherwise
legally in the public domain or is legally obtainable.

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          7.  Confidentiality.
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     7.1  You recognize that during the course of your employment by the
Company, you may have had or may have in the future access to confidential or
proprietary information, including, but not limited to, business documents or
information, research and marketing data, customer lists, computer programs,
processes, techniques, know-how, trade secrets, formulae, manufacturing
processes and inventions, as well as certain information concerning employees,
partners or customers of the Company. This information shall be known as
"Confidential Information" and shall include all information described in the
preceding sentence, whether previously existing, now existing or arising
hereafter, whether conceived or developed by others or by you alone or with
others, and whether or not conceived or developed during regular business hours.
Confidential Information does not include information that legitimately is part
of the public domain, or that has been lawfully disclosed to you by a third
party.

     7.2  You will not, either during the term of your employment with the
Company or thereafter, remove, disclose or cause the disclosure of any
Confidential Information except as removal or disclosure may be required in
connection with your work for the Company. You will take all reasonable steps
necessary to ensure that Confidential Information will not become known to third
parties without the Company's prior written approval.

     7.3  You will not, either during the term of your employment with the
Company or thereafter, use or cause the use of Confidential Information either
for the benefit of yourself or for the benefit of anyone other than the Company,
directly or indirectly.

     8.   Post-Employment Activities.
          --------------------------

     8.1  You understand and acknowledge that the provisions of this Section 8
are necessary to protect the legitimate business interests of the Company and
are fair and reasonable for numerous reasons, including your receipt of the
specific consideration expressed in the second paragraph of this Agreement. In
addition, as a result of your executive position with the Company, you have had,
and will continue to have, access to significant confidential, proprietary or
trade secret information of the Company, so that, if you were employed by a
competitor of the Company, there would be a substantial risk to the Company of
your use of its confidential, proprietary or trade secret information. Based on
the foregoing, for a period of thirty-six (36) months after the termination of
your employment with the Company, absent the Company's prior written approval
(with concurrence from the Board of Directors of ATMI), you will not directly or
indirectly:

          (a)  render any services to, or engage in any activities for, any
     other person, firm, corporation or business organization with respect to
     any product, process, technology or service, in existence or under
     development which substantially resembles or competes with a product,
     process, or service of the Company in existence or under development upon
     which you worked or exercised supervisory responsibility at any time during
     the two (2) years prior to the termination of your employment with the
     Company;

          (b)  solicit employees of the Company to leave their employ or offer
     or cause to be offered employment to any person who is or was employed by
     the Company at any time during the six (6) months prior to the termination
     of your employment with the Company;

          (c)  entice, induce or encourage any of the Company's other employees
     to engage in any activity which, were it done by you, would violate any
     provision of this Section 8; or

          (d)  otherwise attempt to interfere with or disrupt the business or
     activities of the Company or its subsidiaries or affiliates after written
     notice and a 60-day cure period.

You agree that if you act in violation of this Section 8, the number of days
that you are in violation will be added to the time period specified in this
Section 8.

     8.2  Upon your written request to the Company specifying the activities
proposed to be conducted by you, the Company may in its discretion, subject to
the concurrence of the Board of Directors of ATMI, give you written approval(s)
to engage personally in any activity or render services referred to in Section
8.l upon receipt of written assurances (satisfactory to the Company and its
counsel in their discretion) from you and from your prospective employer(s) that
the integrity of the provisions of Section 7 and Section 8.l will not in any way
be jeopardized or violated by such activities; provided, however, the burden of
                                               --------  -------
so establishing the foregoing to the satisfaction of the Company and said
counsel shall be upon you and your prospective employer(s). Failure of the
Company to respond to such written request shall be deemed a rejection of such
request.

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     9.   Remedies. Your duties under Section 7 and Section 8 shall survive
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termination of your employment with the Company. You acknowledge and agree that
any breach by you of any of the provisions of Section 7 or Section 8.1 of this
Agreement will result in irreparable and continuing damage to the Company and
that a remedy at law for any breach or threatened breach by you of the
provisions of Section 7 or Section 8.1 would be inadequate, and you therefore
agree that the Company shall be entitled to temporary, preliminary and permanent
injunctive relief in case of any such breach or threatened breach. The
prevailing party in an action under this Agreement shall be entitled to recover
its costs and expenses, including attorneys' fees. Nothing in this Agreement
shall be construed to prohibit the Company from pursuing any other remedy
available to it at law or in equity, the parties having agreed that all remedies
are cumulative.

     10.  Miscellaneous.
          -------------

     10.1 This Agreement and the rights and obligations of the parties hereto
shall bind and inure to the benefit of any successor or successors of the
Company by reorganization, merger or consolidation and any assignee of all or
substantially all of its business and properties or the business or properties
of the Company or any subsidiary or division thereof, but, except as to any such
successor or assignee of the Company, neither this Agreement nor any rights or
benefits hereunder may be assigned by the Company or you.

     10.2 In case any one or more of the provisions contained in this Agreement
shall, for any reason, be held to be invalid, illegal or unenforceable in any
respect, such invalidity, illegality or unenforceability shall not affect the
other provisions of this Agreement. If moreover, any one or more of the
provisions contained in this Agreement shall for any reason be held to be
excessively broad as to duration, geographical scope, activity or subject, the
parties expressly agree that a court may rewrite and modify such provisions so
as to be enforceable to the fullest extent compatible with the applicable law as
it shall then appear.

     10.3 All notices, consents, waivers, and other communications under this
Agreement must be in writing and will be deemed to have been duly given when (a)
delivered by hand (with written confirmation of receipt), (b) sent by facsimile
(with written confirmation of receipt), provided that a copy is mailed by
registered mail, return receipt requested, or (c) when received by the
addressee, if sent by a nationally recognized overnight delivery service
(receipt requested), in each case to the appropriate addresses and facsimile
numbers set forth below (or to such other addresses and facsimile numbers as a
party may designate by notice to the other parties):

     If to the Company:

          Advanced Technology Materials, Inc.
          7 Commerce Drive
          Danbury, CT 06810
          Facsimile No. (203) 792-8040
          Attention:  Daniel P. Sharkey, CFO

     If to you:

          Douglas A. Neugold
          125 Lake Ridge Road
          Southbury, CT 06844

     10.4 If either party shall waive any breach of any provision of this
Agreement, he or it shall not thereby be deemed to have waived any preceding or
succeeding breach of the same or any other provision of this Agreement.

     10.5 The headings of the sections hereof are inserted for convenience only
and shall not be deemed to constitute a part hereof nor to affect the meaning
hereof.

     10.6 This Agreement shall be governed by and construed (both as to validity
and performance) and enforced in accordance with the laws of the State of
Connecticut applicable to agreements made and to be performed wholly within such
jurisdiction. You hereby agree to accept the non-exclusive jurisdiction of the
courts of the State of Connecticut, and those of the United States of America
situated in the State of Connecticut, for the adjudication of any dispute
arising out of this Agreement. You hereby irrevocably (1) agree that any suit,
action or other legal proceeding arising out of this Agreement may be brought in
any Connecticut or United States federal court located in Connecticut; (2)
consent to the jurisdiction of each such court in any such suit, action, or
legal proceeding; (3) waive any objection which you may have to the laying of
venue of any such suit, action, or legal proceeding in any of such courts; and
(4) agree that Connecticut is the most convenient forum for litigation of any
such suit, action or legal proceeding.

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     10.7 This Agreement, together with the Proprietary Information and
Inventions Agreement, is the entire agreement of the parties with respect to the
subject matter hereof and may not be amended, supplemented, cancelled or
discharged except by written instrument executed by both parties hereto. This
Agreement supersedes any and all prior agreements between the Company and you
with respect to the matters covered hereby.

     10.8 This Agreement may be executed in counterparts, each of which when so
executed and delivered shall constitute a complete and original instrument but
all of which together shall constitute one and the same agreement, and it shall
not be necessary when making proof of this Agreement or any counterpart thereof
to account for any other counterpart.

     10.9 You acknowledge that you had the opportunity to have this Agreement
reviewed by an attorney prior to your execution of this Agreement.

     If you are in agreement with the foregoing, please so indicate by
signing and returning the enclosed copy of this letter.


                                   ADVANCED TECHNOLOGY MATERIALS, INC.



                                   By:_____________________________
                                        Name:
                                        Title:

Accepted and agreed:


_______________________________
Douglas A. Neugold

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