<PAGE>

                                                                   EXHIBIT 10.43

                                LEASE AGREEMENT


                                    between


                    PENINSULA OFFICE PARK ASSOCIATES, L.P.
                                 as "Landlord"


                                      and


                                TRINTECH, INC.
                                  as "Tenant"
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
SECTION                                                                    PAGE
-------                                                                    ----
<S>                                                                        <C>
1.   PREMISES...........................................................      4
2.   TERM; POSSESSION...................................................      4
3.   RENT...............................................................      4
4.   SECURITY DEPOSIT...................................................      8
5.   USE AND COMPLIANCE WITH LAWS.......................................      8
6.   TENANT IMPROVEMENTS & ALTERATIONS..................................     11
7.   MAINTENANCE AND REPAIRS............................................     12
8.   TENANT'S TAXES.....................................................     13
9.   UTILITIES AND SERVICES.............................................     14
10.  EXCULPATION AND INDEMNIFICATION....................................     15
11.  INSURANCE..........................................................     16
12.  DAMAGE OR DESTRUCTION..............................................     18
13.  CONDEMNATION.......................................................     19
14.  ASSIGNMENT AND SUBLETTING..........................................     21
15.  DEFAULT AND REMEDIES...............................................     23
16.  LATE CHARGE AND INTEREST...........................................     25
17.  WAIVER.............................................................     25
18.  ENTRY, INSPECTION AND CLOSURE......................................     26
19.  SURRENDER AND HOLDING OVER.........................................     26
20.  ENCUMBRANCES.......................................................     27
21.  ESTOPPEL CERTIFICATES AND FINANCIAL STATEMENTS.....................     28
22.  NOTICES............................................................     28
23.  ATTORNEYS' FEES....................................................     29
24.  QUIET POSSESSION...................................................     29
25.  SECURITY MEASURES..................................................     29
26.  FORCE MAJEURE......................................................     30
27.  RULES AND REGULATIONS..............................................     30
28.  LANDLORD'S LIABILITY...............................................     30
29.  CONSENTS AND APPROVALS.............................................     30
30.  WAIVER OF RIGHT TO JURY TRIAL......................................     31
31.  BROKERS............................................................     31
32.  RELOCATION OF PREMISES.............................................     31
33.  ENTIRE AGREEMENT...................................................     32
34.  MISCELLANEOUS......................................................     32
35.  AUTHORITY..........................................................     32
</TABLE>

                                      -i-
<PAGE>

                            INDEX OF DEFINED TERMS

<TABLE>
<S>                                                                         <C>
Additional Rent...........................................................   7
Alterations...............................................................  11
Award.....................................................................  19
Base Operating Costs......................................................   5
Base Taxes................................................................   5
Broker....................................................................  31
Building..................................................................   4
Building Rules............................................................  30
Building Systems..........................................................   9
Business Days.............................................................  14
Business Hours............................................................  14
Claims....................................................................  15
Commencement Date.........................................................   4
Condemnation..............................................................  20
Condemnor.................................................................  20
Controls..................................................................  14
Date of Condemnation......................................................  20
Encumbrance...............................................................  28
Environmental Losses......................................................  10
Environmental Requirements,...............................................   9
Event of Default..........................................................  23
Expiration Date...........................................................   4
Fees......................................................................  29
Handled by Tenant.........................................................  10
Handling by Tenant........................................................  10
Hazardous Materials.......................................................   9
HVAC......................................................................   9
Interest Rate.............................................................  25
Landlord..................................................................   4
Laws......................................................................   5
Mortgagee.................................................................  28
Operating Costs...........................................................   5
Parking Facility..........................................................   4
Permitted Hazardous Materials.............................................  10
Premises..................................................................   4
Project...................................................................   4
Property..................................................................   4
Property Manager..........................................................  16
Proposed Transferee.......................................................  21
Rent......................................................................   8
Rental Tax................................................................  14
Representatives...........................................................  10
Security Deposit..........................................................   8
Service Failure...........................................................  15
Taxes.....................................................................   6
Tenant....................................................................   4
Tenant Improvements.......................................................  11
Tenant's Share............................................................   6
Tenant's Taxes............................................................  14
Term......................................................................   4
Trade Fixtures............................................................  12
Transfer..................................................................  21
Transferee................................................................  22
Visitors..................................................................  10
</TABLE>

                                      -ii-
<PAGE>

                            BASIC LEASE INFORMATION

Lease Date:         For identification purposes only, the date of this Lease is
                    May 28, 1999

Landlord:           PENINSULA OFFICE PARK ASSOCIATES, L.P., a California limited
                    partnership

Tenant:             TRINTECH, INC., a California corporation

Project:            Peninsula Office Park

Building:           Peninsula Office Park Five

Building Address:   2755 Campus Drive
                    San Mateo, CA 94403

Rentable Area of
Building:           Approximately 79,642 rentable square feet

Premises:           Floor:              Two
                    Suite Number:       220
                    Rentable Area:      Approximately 7,250 rentable square feet

Term:               60 full calendar months (plus any partial month at the
                    beginning of the Term)

Commencement Date:  Earlier of the date that Tenant occupies the Premises or
                    August 1, 1999, as more specifically contained in Section 2
                    of this Lease

Expiration Date:    The last day of the 60th full calendar month in the Term

Base Rent:          Months 01 - 12:     $3.55 per rentable square foot per month
                    Months 13 - 24:     $3.65 per rentable square foot per month
                    Months 25 - 36:     $3.75 per rentable square foot per month
                    Months 37 - 48:     $3.85 per rentable square foot per month
                    Months 49 - 60:     $3.95 per rentable square foot per month

Base Year:          The calendar year 1999

Tenant's Share:     9.10%

Security Deposit:   (a) Cash of $27,187.00, plus

                                      -1-
<PAGE>

                        (b) a Letter of Credit in the amount of $161,313.00,
                        subject to, and in accordance with, the provisions of
                        Section 36 of this Lease.

Landlord's Address      Peninsula Office Park
for Payment of Rent:    File 72882
                        P.O. Box 61000
                        San Francisco, CA 94161-2882

Business Hours:         8:00 a.m. - 6:00 p.m. (Monday - Friday, except Holidays)

Landlord's Address      PENINSULA OFFICE PARK ASSOCIATES, L.P.
for Notices:            2929 Campus Drive, Suite 145
                        San Mateo, CA 94403
                        Attention: Property Management

                        with a copy to:

                        PENINSULA OFFICE PARK ASSOCIATES, L.P.
                        2929 Campus Drive, Suite 450
                        San Mateo, CA 94403
                        Attention: General Counsel

Tenant's Address
for Notices:            At the Premises

Broker(s):              Wayne Mascia Associates &
                        Commercial Real Estate Services

Guarantor(s):           (none)

Property Manager:       Cornerstone Properties Limited Partnership
                        dba Wilson-Cornerstone Properties Limited Partnership

Additional Provisions:  36.  Letter of Credit
                        37.  Parking

Exhibits:
--------
Exhibit A:     The Premises
Exhibit B:     Construction Rider
Exhibit C:     Building Rules
Exhibit D:     Additional Provisions
Exhibit E:     Approved Letter of Credit Form

                                      -2-
<PAGE>

     The Basic Lease Information set forth above is part of the Lease. In the
event of any conflict between any provision in the Basic Lease Information and
the Lease, the Lease shall control.

                                      -3-
<PAGE>

     THIS LEASE is made as of the Lease Date set forth in the Basic Lease
Information, by and between the Landlord identified in the Basic Lease
Information ("Landlord"), and the Tenant identified in the Basic Lease
Information ("Tenant"). Landlord and Tenant hereby agree as follows:

1.  PREMISES. Landlord hereby leases to Tenant, and Tenant hereby leases from
Landlord, upon the terms and subject to the conditions of this Lease, the office
space identified in the Basic Lease Information as the Premises (the
"Premises"), in the Building located at the address specified in the Basic Lease
Information (the "Building"). The approximate configuration and location of the
Premises is shown on Exhibit A. Landlord and Tenant agree that the rentable area
                     ---------
of the Premises for all purposes under this Lease shall be the Rentable Area
specified in the Basic Lease Information. The Building, together with the
parking facilities serving the Building (the "Parking Facility"), and the
parcel(s) of land on which the Building and the Parking Facility are situated
(collectively, the "Property"), is part of the Project identified in the Basic
Lease Information (the "Project").

2.  TERM; POSSESSION. The term of this Lease (the "Term") shall commence on the
Commencement Date as described below and, unless sooner terminated, shall expire
on the Expiration Date set forth in the Basic Lease Information (the "Expiration
Date"). The "Commencement Date" shall be the earlier of (a) the date upon which
Tenant, with Landlord's written permission, actually occupies and conducts
business in any portion of the Premises; or (b) July 1, 1999. Landlord shall not
be liable for any claims, damages or liabilities if the Premises are not ready
for occupancy by August 1, 1999. When the Commencement Date has been
established, Landlord and Tenant shall at the request of either party confirm
the Commencement Date and Expiration Date in writing.

Tenant understands and agrees that the Premises is currently leased by another
tenant (the "Existing Tenant"). Landlord agrees to use its good faith efforts to
a negotiate lease termination agreement with the Existing Tenant and deliver
possession thereof to Tenant on or before August 1, 1999.

3.  RENT.

     3.1  Base Rent. Tenant agrees to pay to Landlord the Base Rent set forth in
          ---------
the Basic Lease Information, without prior notice or demand, on the first day of
each and every calendar month during the Term, except that Base Rent for the
first full calendar month in which Base Rent is payable shall be paid upon
Tenant's execution of this Lease and Base Rent for any partial month at the
beginning of the Term shall be paid on the Commencement Date. Base Rent for any
partial month at the beginning or end of the Term shall be prorated based on the
actual number of days in the month.

     If the Basic Lease Information provides for any change in Base Rent by
reference to years or months (without specifying particular dates), the change
will take effect on the applicable annual

                                      -4-
<PAGE>

or monthly anniversary of the Commencement Date (which won't necessarily be the
first day of a calendar month).

     3.2  Additional Rent: Increases in Operating Costs and Taxes.
          -------------------------------------------------------

          (a)  Definitions.
               -----------

               (1) "Base Operating Costs" means Operating Costs for the calendar
year specified as the Base Year in the Basic Lease Information (excluding
therefrom, however, any Operating Costs of a nature that would not ordinarily be
incurred on an annual, recurring basis).

               (2) "Base Taxes" means Taxes for the calendar year specified as
the Base Year in the Basic Lease Information.

               (3) "Operating Costs" means all costs of managing, operating,
maintaining and repairing the Property, including all costs, expenditures, fees
and charges for: (A) operation, maintenance and repair of the Property
(including maintenance, repair and replacement of glass, the roof covering or
membrane, and landscaping); (B) utilities and services (including
telecommunications facilities and equipment, recycling programs and trash
removal), and associated supplies and materials; (C) compensation (including
employment taxes and fringe benefits) for persons who perform duties in
connection with the operation, management, maintenance and repair of the
Building, such compensation to be appropriately allocated for persons who also
perform duties unrelated to the Building; (D) property (including coverage for
earthquake and flood if carried by Landlord), liability, rental income and other
insurance relating to the Property, and expenditures for deductible amounts paid
under such insurance; (E) licenses, permits and inspections; (F) complying with
the requirements of any law, statute, ordinance or governmental rule or
regulation or any orders pursuant thereto (collectively "Laws"); (G)
amortization of capital improvements required to comply with Laws, or which are
intended to reduce Operating Costs or improve the utility, efficiency or
capacity of any Building System, with interest on the unamortized balance at the
rate paid by Landlord on funds borrowed to finance such Capital improvements
(or, if Landlord finances such improvements out of Landlord's funds without
borrowing, the rate that Landlord would have paid to borrow such funds, as
reasonably determined by Landlord), over such useful life as Landlord shall
reasonably determine; (H) an office in the Project for the management of the
Property, including expenses of furnishing and equipping such office and the
rental value of any space occupied for such purposes; (I) property management
fees; (J) accounting, legal and other professional services incurred in
connection with the operation of the Property and the calculation of Operating
Costs and Taxes; (K) a reasonable allowance for depreciation on machinery and
equipment used to maintain the Property and on other personal property owned by
Landlord in the Property (including window coverings and carpeting in common
areas); (L) contesting the validity or applicability of any Laws that may affect
the Property; (M) the Building's share of any shared or common area maintenance
fees and expenses (including costs and expenses of operating, managing, owning
and maintaining the Parking Facility and the common areas of the Project and any
fitness center or conference center in the Project); and (N) any other cost,
expenditure, fee or charge, whether or not hereinbefore described, which in

                                      -5-
<PAGE>

accordance with generally accepted property management practices would be
considered an expense of managing, operating, maintaining and repairing the
Property. Operating Costs for any calendar year during which average occupancy
of the Building is less than one hundred percent (100%) shall be calculated
based upon the Operating Costs that would have been incurred if the Building had
an average occupancy of one hundred percent (100%) during the entire calendar
year.

Operating Costs shall not include (i) capital improvements (except as otherwise
provided above); (ii) costs of special services rendered to individual tenants
(including Tenant) for which a special charge is made; (iii) interest and
principal payments on loans or indebtedness secured by the Building; (iv) costs
of improvements for Tenant or other tenants of the Building; (v) costs of
services or other benefits of a type which are not available to Tenant but which
are available to other tenants or occupants, and costs for which Landlord is
reimbursed by other tenants of the Building other than through payment of
tenants' shares of increases in Operating Costs and Taxes; (vi) leasing
commissions, attorneys' fees and other expenses incurred in connection with
leasing space in the Building or enforcing such leases; (vii) depreciation or
amortization, other than as specifically enumerated in the definition of
Operating Costs above; and (viii) costs, fines or penalties incurred due to
Landlord's violation of any Law.

               (4) "Taxes" means: all real property taxes and general, special
or district assessments or other governmental impositions, of whatever kind,
nature or origin, imposed on or by reason of the ownership or use of the
Property; governmental charges, fees or assessments for transit or traffic
mitigation (including area-wide traffic improvement assessments and
transportation system management fees), housing, police, fire or other
governmental service or purported benefits to the Property; personal property
taxes assessed on the personal property of Landlord used in the operation of the
Property; service payments in lieu of taxes and taxes and assessments of every
kind and nature whatsoever levied or assessed in addition to, in lieu of or in
substitution for existing or additional real or personal property taxes on the
Property or the personal property described above; any increases in the
foregoing caused by changes in assessed valuation, tax rate or other factors or
circumstances; and the reasonable cost of contesting by appropriate proceedings
the amount or validity of any taxes, assessments or charges described above. To
the extent paid by Tenant or other tenants as "Tenant's Taxes" (as defined in
Section 8 -Tenant's Taxes), "Tenant's Taxes" shall be excluded from Taxes.

               (5) "Tenant's Share" means the Rentable Area of the Premises
divided by the total Rentable Area of the Building, as set forth in the Basic
Lease Information. If the Rentable Area of the Building is changed or the
Rentable Area of the Premises is changed by Tenant's leasing of additional space
hereunder or for any other reason, Tenant's Share shall be adjusted accordingly.

          (b)  Additional Rent.
               ---------------

               (1) Tenant shall pay Landlord as "Additional Rent" for each
calendar year or portion thereof during the Term Tenant's Share of the sum of
(x) the amount (if any) by

                                      -6-
<PAGE>

which Operating Costs for such period exceed Base Operating Costs, and (y) the
amount (if any) by which Taxes for such period exceed Base Taxes.

               (2) Prior to the end of the Base Year and each calendar year
thereafter, Landlord shall notify Tenant of Landlord's estimate of Operating
Costs, Taxes and Tenant's Additional Rent for the following calendar year.
Commencing on the first day of January of each calendar year and continuing on
the first day of every month thereafter in such year, Tenant shall pay to
Landlord one-twelfth (1/12th) of the estimated Additional Rent. If Landlord
thereafter estimates that Operating Costs or Taxes for such year will vary from
Landlord's prior estimate, Landlord may, by notice to Tenant, revise the
estimate for such year (and Additional Rent shall thereafter be payable based on
the revised estimate).

               (3) As soon as reasonably practicable after the end of the Base
Year and each calendar year thereafter, Landlord shall furnish Tenant a
statement with respect to such year, showing Operating Costs, Taxes and
Additional Rent for the year, and the total payments made by Tenant with respect
thereto. Unless Tenant raises any objections to Landlord's statement within
ninety (90) days after receipt of the same, such statement shall conclusively be
deemed correct and Tenant shall have no right thereafter to dispute such
statement or any item therein or the computation of Additional Rent based
thereon. If Tenant does object to such statement, then Landlord shall provide
Tenant with reasonable verification of the figures shown on the statement and
the parties shall negotiate in good faith to resolve any disputes. Any objection
of Tenant to Landlord's statement and resolution of any dispute shall not
postpone the time for payment of any amounts due Tenant or Landlord based on
Landlord's statement, nor shall any failure of Landlord to deliver Landlord's
statement in a timely manner relieve Tenant of Tenant's obligation to pay any
amounts due Landlord based on Landlord's statement.

               (4) If Tenant's Additional Rent as finally determined for any
calendar year exceeds the total payments made by Tenant on account thereof,
Tenant shall pay Landlord the deficiency within ten (10) days of Tenant's
receipt of Landlord's statement. If the total payments made by Tenant on account
thereof exceed Tenant's Additional Rent as finally determined for such year,
Tenant's excess payment shall be credited toward the rent next due from Tenant
under this Lease. For any partial calendar year at the beginning or end of the
Term, Additional Rent shall be prorated on the basis of a 365-day year by
computing Tenant's Share of the increases in Operating Costs and Taxes for the
entire year and then prorating such amount for the number of days during such
year included in the Term. Notwithstanding the termination of this Lease,
Landlord shall pay to Tenant or Tenant shall pay to Landlord, as the case may
be, within ten (10) days after Tenant's receipt of Landlord's final statement
for the calendar year in which this Lease terminates, the difference between
Tenant's Additional Rent for that year, as finally determined by Landlord, and
the total amount previously paid by Tenant on account thereof.

If for any reason Base Taxes or Taxes for any year during the Term are reduced,
refunded or otherwise changed, Tenant's Additional Rent shall be adjusted
accordingly. If Taxes are temporarily reduced as a result of space in the
Building being leased to a tenant that is entitled to an exemption from property
taxes or other taxes, then for purposes of determining Additional Rent for

                                      -7-
<PAGE>

each year in which Taxes are reduced by any such exemption, Taxes for such year
shall be calculated on the basis of the amount the Taxes for the year would have
been in the absence of the exemption. The obligations of Landlord to refund any
overpayment of Additional Rent and of Tenant to pay any Additional Rent not
previously paid shall survive the expiration of the Term. Notwithstanding
anything to the contrary in this Lease, if there is at any time a decrease in
Taxes below the amount of the Taxes for the Base Year, then for purposes of
calculating Additional Rent for the year in which such decrease occurs and all
subsequent periods, Base Taxes shall be reduced to equal the Taxes for the year
in which the decrease occurs.

     3.3  Payment of Rent. All amounts payable or reimbursable by Tenant under
          ---------------
this Lease, including late charges and interest (collectively, "Rent"), shall
constitute rent and Shall be payable and recoverable as rent in the manner
provided in this Lease. All sums payable to Landlord on demand under the terms
of this Lease shall be payable within ten (10) days after notice from Landlord
of the amounts due. All rent shall be paid without offset, recoupment or
deduction in lawful money of the United States of America to Landlord at
Landlord's Address for Payment of Rent as set forth in the Basic Lease
Information, or to such other person or at such other place as Landlord may from
time to time designate.

4.  SECURITY DEPOSIT. On execution of this Lease, Tenant shall deposit with
Landlord the amount specified in the Basic Lease Information and the letter of
credit identified in Section 36 below as the Security Deposit (collectively, the
"Security Deposit", which term shall include amounts drawn on the letter of
credit), as security for the performance of Tenant's obligations under this
Lease. Landlord may (but shall have no obligation to) use the Security Deposit
or any portion thereof to cure any breach or default by Tenant under this Lease,
to fulfill any of Tenant's obligations under the Lease, or to compensate
Landlord for any damage it incurs as a result of Tenant's failure to perform any
of Tenant's obligations hereunder. In such event, Tenant shall pay to Landlord
on demand an amount sufficient to replenish the Security Deposit to the full
amount of the cash specified in the Basic Lease Information and the applicable
Face Amount (defined in Section 36 below) of the letter of credit. If at the
expiration or termination of this Lease, Tenant is not in default, has otherwise
fully performed all of Tenant's obligations under this Lease, and there are no
outstanding Claims (defined in Section 10.1 below, and including all existing
and potential Claims) for which Tenant is responsible, Landlord shall return to
Tenant the Security Deposit or the balance thereof then held by Landlord and not
applied as provided above. Landlord may commingle the Security Deposit with
Landlord's general and other funds. Landlord shall not be required to pay
interest on the Security Deposit to Tenant. Tenant acknowledges that Landlord
has agreed to accept a letter of credit in lieu of an additional cash deposit as
an accommodation to Tenant and Tenant agrees that the letter of credit and all
amounts drawn thereunder shall be treated for all purposes under this Lease as
if a cash deposit had been tendered to Landlord upon the execution of this
Lease.

5.   USE AND COMPLIANCE WITH LAWS.

     5.1  Use. The Premises shall be used and occupied for general business
     ---
office purposes and for no other use or purpose. Tenant shall comply with all
present and future Laws relating to

                                      -8-
<PAGE>

Tenant's use or occupancy of the Premises (and make any repairs, alterations or
improvements as required to comply with all such Laws), and shall observe the
"Building Rules" (as defined in Section 27 - Rules and Regulations). Tenant
shall not do, bring, keep or sell anything in or about the Premises that is
prohibited by, or that will cause a cancellation of or an increase in the
existing premium for, any insurance policy covering the Property or any part
thereof. Tenant shall not permit the Premises to be occupied or used in any
manner that will constitute waste or a nuisance, or disturb the quiet enjoyment
of or otherwise annoy other tenants in the Building. Without limiting the
foregoing, the Premises shall not be used for educational activities, practice
of medicine or any of the healing arts, providing social services, for any
governmental use (including embassy or consulate use), or for personnel agency,
customer service office, studios for radio, television or other media, travel
agency or reservation center operations or uses. Tenant shall not, without the
prior consent of Landlord, (i) bring into the Building or the Premises anything
that may cause substantial noise, odor or vibration, overload the floors in the
Premises or the Building or any of the heating, ventilating and air-conditioning
("HVAC"), mechanical, elevator, plumbing, electrical, fire protection, life
safety, security or other systems in the Building ("Building Systems"), or
jeopardize the structural integrity of the Building or any part thereof; (ii)
connect to the utility systems of the Building any apparatus, machinery or other
equipment other than typical office equipment; or (iii) connect to any
electrical circuit in the Premises any equipment or other load with aggregate
electrical power requirements in excess of 80% of the rated capacity of the
circuit.

     5.2  Hazardous Materials
          -------------------

          (a)  Definitions.
               -----------

               (1) "Hazardous Materials" shall mean any substance: (A) that now
or in the future is regulated or governed by, requires investigation or
remediation under, or is defined as a hazardous waste, hazardous substance,
pollutant or contaminant under any governmental statute, code, ordinance,
regulation, rule or order, and any amendment thereto, including the
Comprehensive Environmental Response Compensation and Liability Act, 42 U.S.C.
(S) 9601 et seq., and the Resource Conservation and Recovery Act, 42 U.S.C.
         -- ---
(S)6901 et seq., or (B) that is toxic, explosive, corrosive, flammable,
        -- ---
radioactive, carcinogenic, dangerous or otherwise hazardous, including gasoline,
diesel fuel, petroleum hydrocarbons, polychlorinated biphenyls (PCBs), asbestos,
radon and urea formaldehyde foam insulation.

               (2) "Environmental Requirements" shall mean all present and
future Laws, orders, permits, Licenses, approvals, authorizations and other
requirements of any kind applicable to Hazardous Materials.

               (3) "Handled by Tenant" and "Handling by Tenant" shall mean and
refer to any installation, handling, generation, storage, use, disposal,
discharge, release, abatement, removal, transportation, or any other activity of
any type by Tenant or its agents, employees, contractors, licensees, assignees,
sublessees, transferees or representatives(collectively,

                                      -9-
<PAGE>

"Representatives") or its guests, customers, invitees, or visitors
(collectively, "Visitors"), at or about the Premises in connection with or
involving Hazardous Materials.

               (4) "Environmental Losses" shall mean all costs and expenses of
any kind, damages, including foreseeable and unforeseeable consequential
damages, fines and penalties incurred in connection with any violation of and
compliance with Environmental Requirements and all losses of any kind
attributable to the diminution of value, loss of use or adverse effects on
marketability or use of any portion of the Premises or Property.

          (b) Tenant's Covenants. No Hazardous Materials shall be Handled by
              ------------------
Tenant at or about the Premises or Property without Landlord's prior written
consent, which consent may be granted, denied, or conditioned upon compliance
with Landlord's requirements, all in Landlord's absolute discretion.
Notwithstanding the foregoing, normal quantities and use of those Hazardous
Materials customarily used in the conduct of general office activities, such as
copier fluids and cleaning supplies ("Permitted Hazardous Materials"), may be
used and stored at the Premises without Landlord's prior written consent,
provided that Tenant's activities at or about the Premises and Property and the
Handling by Tenant of all Hazardous Materials shall comply at all times with all
Environmental Requirements. At the expiration or termination of the Lease,
Tenant shall promptly remove from the Premises and Property all Hazardous
Materials Handled by Tenant at the Premises or the Property. Tenant shall keep
Landlord fully and promptly informed of all Handling by Tenant of Hazardous
Materials other than Permitted Hazardous Materials. Tenant shall be responsible
and liable for the compliance with all of the provisions of this Section by all
of Tenant's Representatives and Visitors, and all of Tenant's obligations under
this Section (including its indemnification obligations under paragraph (e)
below) shall survive the expiration or termination of this Lease.

          (c) Compliance. Tenant shall at Tenant's expense promptly take all
              ----------
actions required by any governmental agency or entity in connection with or as a
result of the Handling by Tenant of Hazardous Materials at or about the Premises
or Property, including inspection and testing, performing all cleanup, removal
and remediation work required with respect to those Hazardous Materials,
complying with all closure requirements and post-closure monitoring, and filing
all required reports or plans. All of the foregoing work and all Handling by
Tenant of all Hazardous Materials shall be performed in a good, safe and
workmanlike manner by consultants qualified and licensed to undertake such work
and in a manner that will not interfere with any other tenant's quiet enjoyment
of the Property or Landlord's use, operation, leasing and sale of the Property.
Tenant shall deliver to Landlord prior to delivery to any governmental agency,
or promptly after receipt from any such agency, copies of all permits,
manifests, closure or remedial action plans, notices, and all other documents
relating to the Handling by Tenant of Hazardous Materials at or about the
Premises or Property. If any lien attaches to the Premises or the Property in
connection with or as a result of the Handling by Tenant of Hazardous Materials,
and Tenant does not cause the same to be released, by payment, bonding or
otherwise, within ten (10) days after the attachment thereof, Landlord shall
have the right but not the obligation to cause the same to be released and any
sums expended by Landlord (plus Landlord's administrative costs) in connection
therewith shall be payable by Tenant on demand.

                                      -10-
<PAGE>

          (d) Landlord's Rights. Landlord shall have the right, but not the
              -----------------
obligation, to enter the Premises at any reasonable time (i) to confirm Tenant's
compliance with the provisions of this Section 5.2, and (ii) to perform Tenant's
obligations under this Section if Tenant has failed to do so after reasonable
notice to Tenant. Landlord shall also have the right to engage qualified
Hazardous Materials consultants to inspect the Premises and review the Handling
by Tenant of Hazardous Materials, including review of all permits, reports,
plans, and other documents regarding same. Tenant shall pay to Landlord on
demand the costs of Landlord's consultants' fees and all costs incurred by
Landlord in performing Tenant's obligations under this Section. Landlord shall
use reasonable efforts to minimize any interference with Tenant's business
caused by Landlord's entry into the Premises, but Landlord shall not be
responsible for any interference caused thereby.

          (e) Tenant's Indemnification. Tenant agrees to indemnify, defend,
              ------------------------
protect and hold harmless Landlord and its partners or members and its or their
partners, members, directors, officers, shareholders, employees and agents from
all Environmental Losses and all other claims, actions, losses, damages,
liabilities, costs and expenses of every kind, including reasonable attorneys,
experts' and consultants' fees and costs, incurred at any time and arising from
or in connection with the Handling by Tenant of Hazardous Materials at or about
the Property or Tenant's failure to comply in full with all Environmental
Requirements with respect to the Premises.

6.   TENANT IMPROVEMENTS & ALTERATIONS.

     6.1  Landlord and Tenant shall perform their respective obligations with
respect to design and construction of any improvements to be constructed and
installed in the Premises (the "Tenant Improvement"), as provided in the
Construction Rider. Except for any Tenant Improvements to be constructed by
Tenant as provided in the Construction Rider, Tenant shall not make any
alterations, improvements or changes to the Premises, including installation of
any security system or telephone or data communication wiring, ("Alterations"),
without Landlord's prior written consent. Any such Alterations shall be
completed by Tenant at Tenant's sole cost and expense: (i) with due diligence,
in a good and workmanlike manner, using new materials; (ii) in compliance with
plans and specifications approved by Landlord; (iii) in compliance with the
construction rules and regulations promulgated by Landlord from time to time;
(iv) in accordance with all applicable Laws (including all work, whether
structural or non-structural, inside or outside the Premises, required to comply
fully with all applicable Laws and necessitated by Tenant's work); and (v)
subject to all conditions which Landlord may in Landlord's discretion impose.
Such conditions may include requirements for Tenant to: (i) provide payment or
performance bonds or additional insurance (from Tenant or Tenant's contractors,
subcontractors or design professionals); (ii) use contractors or subcontractors
designated by Landlord; and (iii) remove all or part of the Alterations prior to
or upon expiration or termination of the Term, as designated by Landlord. If any
work outside the Premises, or any work on or adjustment to any of the Building
Systems, is required in connection with or as a result of Tenant's work, such
work shall be performed at Tenant's expense by contractors designated by
Landlord. Landlord's right to review and approve (or withhold approval of)
Tenant's plans, drawings, specifications, contractor(s)and other aspects

                                      -11-
<PAGE>

of construction work proposed by Tenant is intended solely to protect Landlord,
the Property and Landlord's interests. No approval or consent by Landlord shall
be deemed or construed to be a representation or warranty by Landlord as to the
adequacy, sufficiency, fitness or suitability thereof or compliance thereof with
applicable Laws or other requirements. Except as otherwise provided in
Landlord's consent, all Alterations shall upon installation become part of the
realty and be the property of Landlord.

     6.2  Before making any Alterations, Tenant shall submit to Landlord for
Landlord's prior approval reasonably detailed final plans and specifications
prepared by a licensed architect or engineer, a copy of the construction
contract, including the name of the contractor and all subcontractors proposed
by Tenant to make the alterations and a copy of the contractor's license. Tenant
shall reimburse Landlord upon demand for any expenses incurred by Landlord in
connection with any Alterations made by Tenant, including reasonable fees
charged by Landlord's contractors or consultants to review plans and
specifications prepared by Tenant and to update the existing as-built plans and
specifications of the Building to reflect the Alterations. Tenant shall obtain
all applicable permits, authorizations and governmental approvals and deliver
copies of the same to Landlord before commencement of any Alterations.

     6.3  Tenant shall keep the Premises and the Property free and clear of all
liens arising out of any work performed, materials furnished or obligations
incurred by Tenant. If any such lien attaches to the Premises or the Property,
and Tenant does not cause the same to be released by payment, bonding or
otherwise within ten (10) days after the attachment thereof, Landlord shall have
the right but not the obligation to cause the same to be released, and any sums
expended by Landlord (plus Landlord's administrative costs) in connection
therewith shall be payable by Tenant on demand with interest thereon from the
date of expenditure by Landlord at the Interest Rate (as defined in Section 16.2
- Interest). Tenant shall give Landlord at least ten (10) days' notice prior to
the commencement of any Alterations and cooperate with Landlord in posting and
maintaining notices of non-responsibility in connection therewith.

     6.4  Subject to the provisions of Section 5 - Use and Compliance with Laws
and the foregoing provisions of this Section, Tenant may install and maintain
furnishings, equipment, movable partitions, business equipment and other trade
fixtures ("Trade Fixtures") in the Premises, provided that the Trade Fixtures do
not become an integral part of the Premises or the Building. Tenant shall
promptly repair any damage to the Premises or the Building caused by any
installation or removal of such Trade Fixtures.

7.   MAINTENANCE AND REPAIRS.

     7.1  By taking possession of the Premises Tenant agrees that the Premises
are then in a good and tenantable condition. During the Term, Tenant at Tenant's
expense but under the direction of Landlord, shall repair and maintain the
Premises, including the interior walls, floor coverings, ceiling (ceiling tiles
and grid), Tenant Improvements, Alterations, fire extinguishers, outlets and
fixtures, and any appliances (including dishwashers, hot water heaters and
garbage

                                      -12-
<PAGE>

disposers) in the Premises, in a first class condition, and keep the Premises in
a clean, safe and orderly condition.

     7.2  Landlord shall maintain or cause to be maintained in reasonably good
order, condition and repair, the structural portions of the roof, foundations,
floors and exterior walls of the Building, the Building Systems, and the public
and common areas of the Property, such as elevators, stairs, corridors and
restrooms; provided, however, that Tenant shall pay the cost of repairs for any
damage occasioned by Tenant's use of the Premises or the Property or any act or
omission of Tenant or Tenant's Representatives or Visitors, to the extent (if
any) not covered by Landlord's property insurance. Landlord shall be under no
obligation to inspect the Premises. Tenant shall promptly report in writing to
Landlord any defective condition known to Tenant which Landlord is required to
repair. As a material part of the consideration for this Lease, Tenant hereby
waives any benefits of any applicable existing or future Law, including the
provisions of California Civil Code Sections 1932(1), 1941 and 1942, that allows
a tenant to make repairs at its landlord's expense.

     7.3  Landlord hereby reserves the right, at any time and from time to time,
without liability to Tenant, and without constituting an eviction, constructive
or otherwise, or entitling Tenant to any abatement of rent or to terminate this
Lease or otherwise releasing Tenant from any of Tenant's obligations under this
Lease:

          (a) To make alterations, additions, repairs, improvements to or in or
to decrease the size of area of, all or any part of the Building, the fixtures
and equipment therein, and the Building Systems;

          (b) To change the Building's name or street address;

          (c) To install and maintain any and all signs on the exterior and
interior of the Building;

          (d) To reduce, increase, enclose or otherwise change at any time and
from time to time the size, number, location, lay-out and nature of the common
areas (including the Parking Facility) and other tenancies and premises in the
Property and to create additional rentable areas through use or enclosure of
common areas; and

          (e) If any governmental authority promulgates or revises any Law or
imposes mandatory or voluntary controls or guidelines on Landlord or the
Property relating to the use or conservation of energy or utilities or the
reduction of automobile or other emissions or reduction or management of traffic
or parking on the Property (collectively "Controls"), to comply with such
Controls, whether mandatory or voluntary, or make any alterations to the
Property related thereto.

8.  TENANT'S TAXES. "Tenant's Taxes" shall mean (a) all taxes, assessments,
license fees and other governmental charges or impositions levied or assessed
against or with respect to Tenant's personal property or Trade Fixtures in the
Premises, whether any such imposition is levied

                                      -13-
<PAGE>

directly against Tenant or levied against Landlord or the Property, (b) all
rental, excise, sales or transaction privilege taxes arising out of this Lease
(excluding, however, state and federal personal or corporate income taxes
measured by the income of Landlord from all sources) imposed by any taxing
authority upon Landlord or upon Landlord's receipt of any rent payable by Tenant
pursuant to the terms of this Lease ("Rental Tax"), and (c) any increase in
Taxes attributable to inclusion of a value placed on Tenant's personal property,
Trade Fixtures or Alterations. Tenant shall pay any Rental Tax to Landlord in
addition to and at the same time as Base Rent is payable under this Lease, and
shall pay all other Tenant's Taxes before delinquency (and, at Landlord's
request, shall furnish Landlord satisfactory evidence thereof). If Landlord pays
Tenant's Taxes or any portion thereof, Tenant shall reimburse Landlord upon
demand for the amount of such payment, together with interest at the Interest
Rate from the date of Landlord's payment to the date of Tenant's reimbursement.

9.   UTILITIES AND SERVICES.

     9.1  Description of Services. Landlord shall furnish to the Premises:
          -----------------------
reasonable amounts of heat, ventilation and air-conditioning during the Business
Hours specified in the Basic Lease Information ("Business Hours") on weekdays
except public holidays ("Business Days"); reasonable amounts of electricity; and
janitorial services five days a week (except public holidays). Landlord shall
also provide the Building with normal fluorescent tube replacement, window
washing, elevator service, and common area toilet room supplies. Any additional
utilities or services that Landlord may agree to provide (including lamp or tube
replacement for other than Building Standard lighting fixtures) shall be at
Tenant's sole expense.

     9.2  Payment for Additional Utilities and Services.
          ---------------------------------------------

          (a) Upon request by Tenant in accordance with the procedures
established by Landlord from time to time for furnishing HVAC service at times
other than Business Hours on Business Days, Landlord shall furnish such service
to Tenant and Tenant shall pay for such services on an hourly basis at the then
prevailing rate established for the Building by Landlord.

          (b) If the temperature otherwise maintained in any portion of the
Premises by the HVAC systems of the Building is affected as a result of (i) any
lights, machines or equipment used by Tenant in the Premises, or (ii) the
occupancy of the Premises by more than one person per 150 square feet of
rentable area, then Landlord shall have the right to install any machinery or
equipment reasonably necessary to restore the temperature, including
modifications to the standard air-conditioning equipment. The cost of any such
equipment and modifications, including the cost of installation and any
additional cost of operation and maintenance of the same, shall be paid by
Tenant to Landlord upon demand.

          (c) If Tenant's usage of electricity, water or any other utility
service exceeds the use of Such utility Landlord determines to be typical,
normal and customary for the Building, Landlord may determine the amount of such
excess use by any reasonable means (including the installation at Landlord's
request but at Tenant's expense of a separate meter or other measuring

                                      -14-
<PAGE>

device) and charge Tenant for the cost of such excess usage. In addition,
Landlord may impose a reasonable charge for the use of any additional or unusual
janitorial services required by Tenant because of any unusual Tenant
Improvements or Alterations, the carelessness of Tenant or the nature of
Tenant's business (including hours of operation).

     9.3  Interruption of Services. In the event of an interruption in or
          ------------------------
failure or inability to provide any services or utilities to the Premises or
Building for any reason (a "Service Failure"), such Service Failure shall not,
regardless of its duration, impose upon Landlord any liability whatsoever,
constitute an eviction of Tenant, constructive or otherwise, entitle Tenant to
an abatement of rent or to terminate this Lease or otherwise release Tenant from
any of Tenant's obligations under this Lease. Tenant hereby waives any benefits
of any applicable existing or future Law, including the provisions of California
Civil Code Section 1932(1), permitting the termination of this Lease due to such
interruption, failure or inability.

10.  EXCULPATION AND INDEMNIFICATION.

     10.1  Landlord's Indemnification of Tenant. Landlord shall indemnify,
           ------------------------------------
protect, defend and hold Tenant harmless from and against any claims, actions,
liabilities, damages, costs or expenses, including reasonable attorneys' fees
and costs incurred in defending against the same ("Claims") assorted by any
third party against Tenant for loss, injury or damage, to the extent such loss,
injury or damage is caused by the willful misconduct or negligent acts or
omissions of Landlord or its authorized representatives.

     10.2  Tenant's Indemnification of Landlord. Tenant shall indemnify,
           ------------------------------------
protect, defend and hold Landlord and Landlord's authorized representatives
harmless from and against Claims arising from (a) the acts or omissions of
Tenant or Tenant's Representatives or Visitors in or about the Property, or (b)
any construction or other work undertaken by Tenant on the Premises (including
any design defects), or (c) any breach or default under this Lease by Tenant, or
(d) any loss, injury or damage, howsoever and by whomsoever caused, to any
person or property, occurring in or about the Premises during the Term,
excepting only Claims described in this clause (d) to the extent they are caused
by the willful misconduct or negligent acts or omissions of Landlord or its
authorized representatives.

     10.3  Damage to Tenant and Tenant's Property. Landlord shall not be liable
           --------------------------------------
to Tenant for any loss, injury or other damage to Tenant or to Tenant's property
in or about the Premises or the Property from any cause (including defects in
the Property or in any equipment in the Property; fire, explosion or other
casualty; bursting, rupture, leakage or overflow of any plumbing or other pipes
or lines, sprinklers, tanks, drains, drinking fountains or washstands in, above,
or about the Premises or the Property; or acts of other tenants in the
Property). Tenant hereby waives all claims against Landlord for any such loss,
injury or damage and the cost and expense of defending against claims relating
thereto, including any loss, injury or damage caused by Landlord's negligence
(active or passive) or willful misconduct. Notwithstanding any other provision
of this Lease to the contrary, in no event shall Landlord be liable to Tenant
for any punitive or consequential damages or damages for loss of business by
Tenant.

                                      -15-
<PAGE>

     10.4  Survival. The obligations of the parties under this Section l0 shall
           --------
survive the expiration or termination of this Lease.

11.  INSURANCE.

     11.1 Tenant's Insurance.
          ------------------

          (a) Liability Insurance Tenant shall maintain in full force throughout
              --------------------
the Term, commercial general liability insurance providing coverage on an
occurrence form basis with limits of not less than Two Million Dollars
($2,000,000.00)each occurrence for bodily injury and property damage combined,
Two Million Dollars ($2,000,000.00) annual general aggregate, and Two Million
Dollars ($2,000,000.00) products and completed operations annual aggregate.
Tenant's liability insurance policy or policies shall: (i) include premises and
operations liability coverage, products and completed operations liability
coverage, broad form property damage coverage including completed operations,
blanket contractual liability coverage including, to the maximum extent
possible, coverage for the indemnification obligations of Tenant under this
Lease, and personal and advertising injury coverage; (ii) provide that the
insurance company has the duty to defend all insureds under the policy; (iii)
provide that defense costs are paid in addition to and do not deplete any of the
policy limits; (iv) cover liabilities arising out of or incurred in connection
with Tenant's use or occupancy of the Premises or the Property; (v) extend
coverage to cover liability for the actions of Tenant's Representatives and
Visitors; and (vi) designate separate limits for the Property. Each policy of
liability insurance required by this Section shall: (i) contain a cross
liability endorsement or separation of insureds clause; (ii) provide that any
waiver of subrogation rights or release prior to a loss does not void coverage;
(iii) provide that it is primary to and not contributing with, any policy of
insurance carried by Landlord covering the same loss; (iv) provide that any
failure to comply with the reporting provisions shall not affect coverage
provided to Landlord, its partners, property managers and Mortgagees; and (v)
name Landlord, its partners, the Property Manager identified in the Basic Lease
Information(the "Property Manager"), and such other parties in interest as
Landlord may from time to time reasonably designate to Tenant in writing, as
additional insureds. Such additional insureds shall be provided at least the
same extent of coverage as is provided to Tenant under such policies. All
endorsements effecting such additional insured status shall be at least as broad
as additional insured endorsement form number CG 20 11 11 85 promulgated by the
Insurance Services Office.

          (b) Property Insurance. Tenant shall at all times maintain in effect
              ------------------
with respect to any Alterations and Tenant's Trade Fixtures and personal
property, commercial property insurance providing coverage, on an "all risk" or
"special form" basis, in an amount equal to at least 90% of the full replacement
cost of the covered property. Tenant may carry such insurance under a blanket
policy, provided that such policy provides coverage equivalent to a separate
policy. During the Term, the proceeds from any such policies of insurance shall
be used for the repair or replacement of the Alterations, Trade Fixtures and
personal property so insured. Landlord shall be provided coverage under such
insurance to the extent of its insurable interest and, if requested by Landlord,
both Landlord and Tenant shall sign all documents reasonably necessary or proper
in

                                      -16-
<PAGE>

connection with the settlement of any claim or loss under such insurance.
Landlord will have no obligation to carry insurance on any Alterations or on
Tenant's Trade Fixtures or personal property.

          (c) Requirements For All Policies. Each policy of insurance required
              -----------------------------
under this Section 11.1 shall: (i) be in a form, and written by an insurer,
reasonably acceptable to Landlord; (ii) be maintained at Tenant's sole cost and
expense, and (iii) require at least thirty (30) days' written notice to Landlord
prior to any cancellation, nonrenewal or modification of insurance coverage.
Insurance companies issuing such, policies shall have rating classifications of
"A" or better and financial size category ratings of "VII" or better according
to the latest edition of the A.M. Best Key Rating Guide. All insurance companies
issuing such policies shall be admitted carriers licensed to do business in the
state where the Property is located. Any deductible amount under such insurance
shall not exceed $5,000. Tenant shall provide to Landlord, upon request,
evidence that the insurance required to be carried by Tenant pursuant to this
Section, including any endorsement effecting the additional insured status, is
in full force and effect and that premiums therefor have been paid.

          (d) Updating Coverage. Tenant shall increase the amounts of insurance
              -----------------
as required by any Mortgagee, and, not more frequently than once every three (3)
years, as recommended by Landlord's insurance broker, if, in the opinion of
either of them, the amount of insurance then required under this Lease is not
adequate. Any limits set forth in this Lease on the amount or type of coverage
required by Tenant's insurance shall not limit the liability of Tenant under
this Lease.

          (e) Certificates of Insurance Prior to occupancy of the Premises by
              -------------------------
Tenant, and not less than thirty (30) days prior to expiration of any policy
thereafter, Tenant shall furnish to Landlord a certificate of insurance
reflecting that the insurance required by this Section is in force, accompanied
by an endorsement showing the required additional insureds satisfactory to
Landlord in substance and form. Notwithstanding the requirements of this
paragraph, Tenant shall at Landlord's request provide to Landlord a certified
copy of each insurance policy required to be in force at any time pursuant to
the requirements of this Lease or its Exhibits.

     11.2  Landlord's Insurance During the Term, to the extent such coverages
           --------------------
are available at a commercially reasonable cost, Landlord shall maintain in
effect insurance on the Building with responsible insurers, on an "all risk" or
"special form" basis, insuring the Building and the Tenant Improvements in an
amount equal to at least 90% of the replacement cost thereof, excluding land,
foundations, footings and underground installations. Landlord may, but shall not
be obligated to, carry insurance against additional perils and/or in greater
amounts.

     11.3  Mutual Waiver of Right of Recovery & Waiver of Subrogation. Landlord
           ----------------------------------------------------------
and Tenant each hereby waive any right of recovery against each other and the
partners, managers, members, shareholders, officers, directors and authorized
representatives of each other for any loss or damage that is covered by any
policy of property insurance maintained by either party (or required by this
Lease to be maintained) with respect to the Premises or the Property or any
operation therein, regardless of cause, including negligence (active or passive)
of the party

                                      -17-
<PAGE>

benefiting from the waiver. If any such policy of insurance relating to this
Lease or to the Premises or the Property does not permit the foregoing waiver or
if the coverage under any such policy would be invalidated as a result of such
waiver, the party maintaining such policy shall obtain from the insurer under
such policy a waiver of all right of recovery by way of subrogation against
either party in connection with any claim, loss or damage covered by such
policy.

12.  DAMAGE OR DESTRUCTION.

     12.1  Landlord's Duty to Repair.
           -------------------------

           (a) If all or a substantial part of the Premises are rendered
untenantable or inaccessible by damage to all or any part of the Property from
fire or other casualty then, unless either party is entitled to and elects to
terminate this Lease pursuant to Sections 12.2 - Landlord's Right to Terminate
and 12.3 - Tenant's Right to Terminate, Landlord shall, at its expense, use
reasonable efforts to repair and restore the Premises and/or the Property, as
the case may be, to substantially their former condition to the extent permitted
by then applicable Laws; provided, however, that in no event shall Landlord have
any obligation for repair or restoration beyond the extent of insurance proceeds
received by Landlord for such repair or restoration, or for any of Tenant's
personal property, Trade Fixtures or Alterations.

           (b) If Landlord is required or elects to repair damage to the
Premises and/or the Property, this Lease shall continue in effect, but Tenant's
Base Rent and Additional Rent shall be abated with regard to any portion of the
Premises that Tenant is prevented from using by reason of such damage or its
repair from the date of the casualty until substantial completion of Landlord's
repair of the affected portion of the Premises as required under this Lease. In
no event shall Landlord be liable to Tenant by reason of any injury to or
interference with Tenant's business or property arising from fire or other
casualty or by reason of any repairs to any part of the Property necessitated by
such casualty.

     12.2  Landlord's Right to Terminate. Landlord may elect to terminate this
           -----------------------------
Lease following damage by fire or other casualty under the following
circumstances:

          (a) If, in the reasonable judgment of Landlord, the Premises and the
Property cannot be substantially repaired and restored under applicable Laws
within one (1) year from the date of the casualty;

          (b) If, in the reasonable judgment of Landlord, adequate proceeds are
not, for any reason, made available to Landlord from Landlord's insurance
policies (and/or from Landlord's funds made available for such purpose, at
Landlord's sole option) to make the required repairs;

          (c) If the Building is damaged or destroyed to the extent that, in the
reasonable judgment of Landlord, the cost to repair and restore the Building
would exceed twenty-five percent (25%) of the full replacement cost of the
Building, whether or not the Premises are at all damaged or destroyed; or

                                      -18-
<PAGE>

          (d) If the fire or other casualty occurs during the last year of the
     Term.

If any of the circumstances described in subparagraphs (a), (b), (c) or (d) of
this Section 12.2 occur or arise, Landlord shall give Tenant notice within one
hundred and twenty (120) days after the date of the casualty, specifying whether
Landlord elects to terminate this Lease as provided above and, if not,
Landlord's estimate of the time required to complete Landlord's repair
obligations under this Lease.

     12.3  Tenant's Right to Terminate. If all or a substantial part of the
           ---------------------------
Premises are rendered untenantable or inaccessible by damage to all or any part
of the Property from fire or other casualty, and Landlord does not elect to
terminate as provided above, then Tenant may elect to terminate this Lease if
Landlord's estimate of the time required to complete Landlord's repair
obligations under this Lease is greater than one (l) year, in which event Tenant
may elect to terminate this Lease by giving Landlord notice of such election to
terminate within thirty (30) days after Landlord's notice to Tenant pursuant to
Section 12.2 - Landlord's Right to Terminate.

     12.4  Waiver. Landlord and Tenant each hereby waive the provisions of
           ------
California Civil Code Sections 1932(2), 1933(4) and any other applicable
existing or future Law permitting the termination of a lease agreement in the
event of damage or destruction under any circumstances other than as provided in
Sections 12.2 - Landlord's Right to Terminate and 12.3 - Tenant's Right to
Terminate.

13.  CONDEMNATION.

     13.1  Definitions.
           -----------

           (a) "Award" shall mean all compensation, sums, or anything of value
awarded, paid or received on a total or partial Condemnation.

           (b) "Condemnation" shall mean (i) a permanent taking (or a temporary
taking for a period extending beyond the end of the Term) pursuant to the
exercise of the power of condemnation or eminent domain by any public or quasi-
public authority, private corporation or individual having such power
("Condemnor"), whether by legal proceedings or otherwise, or (ii) a voluntary
sale or transfer by Landlord to any such authority, either under threat of
condemnation or while legal proceedings for condemnation are pending.

           (c) "Date of Condemnation" shall mean the earlier of the date that
title to the property taken is vested in the Condemnor or the date the Condemnor
has the right to possession of the property being condemned.

                                      -19-
<PAGE>

     13.2  Effect on Lease.
           ---------------

           (a) If the Premises are totally taken by Condemnation, this Lease
shall terminate as of the Date of Condemnation. If a portion but not all of the
Premises is taken by Condemnation, this Lease shall remain in effect; provided,
however, that if the portion of the Premises remaining after the Condemnation
will be unsuitable for Tenant's continued use, then upon notice to Landlord
within thirty (30) days after Landlord notifies Tenant of the Condemnation,
Tenant may terminate this Lease effective as of the Date of Condemnation.

           (b) If twenty-five percent (25%) or more of the Project or of the
parcel(s) of land on which the Building is situated or of the Parking Facility
or of the floor area in the Building is taken by Condemnation, or if as a result
of any Condemnation the Building is no longer reasonably suitable for use as an
office building, whether or not any portion of the Premises is taken, Landlord
may elect to terminate this Lease, effective as of the Date of Condemnation, by
notice to Tenant within thirty (30) days after the Date of Condemnation.

           (c) If all or a portion of the Premises is temporarily taken by a
Condemnor for a period not extending beyond the end of the Term, this Lease
shall remain in full force and effect.

     13.3  Restoration If this Lease is not terminated as provided in Section
           -----------
13.2 - Effect on Lease, Landlord, at its expense, shall diligently proceed to
repair and restore the Premises to substantially its former condition (to the
extent permitted by then applicable Laws) and/or repair and restore the Building
to an architecturally complete office building; provided, however, that
Landlord's obligations to so repair and restore shall be limited to the amount
of any Award received by Landlord and not required to be paid to any Mortgagee
(as defined in Section 20.2 below). In no event shall Landlord have any
obligation to repair or replace any improvements in the Premises beyond the
amount of any Award received by Landlord for such repair or to repair or replace
any of Tenant's personal property, Trade Fixtures, or Alterations.

     13.4  Abatement and Reduction of Rent. If any portion of the Premises is
           -------------------------------
taken in a Condemnation or is rendered permanently untenantable by repairs
necessitated by the Condemnation, and this Lease is not terminated, the Base
Rent and Additional Rent payable under this Lease shall be proportionally
reduced as of the Date of Condemnation based upon the percentage of rentable
square feet in the Premises so taken or rendered permanently untenantable In
addition, if this Lease remains in effect following a Condemnation and Landlord
proceeds to repair and restore the Premises, the Base Rent and Additional Rent
payable under this Lease shall be abated during the period of such repair or
restoration to the extent such repairs prevent Tenant's use of the Premises.

     13.5  Awards. Any Award made shall be paid to Landlord, and Tenant hereby
           ------
assigns to Landlord, and waives all interest in or claim to, any such Award,
including any claim for the value of the unexpired Term; provided, however, that
Tenant shall be entitled to receive, or to prosecute a separate claim for, an
Award for a temporary taking of the Premises or a portion thereof by a Condemnor
where this Lease is not terminated (to the extent such Award relates to the
unexpired

                                      -20-
<PAGE>

Term), or an Award or portion thereof separately designated for relocation
expenses or the interruption of or damage to Tenant's business or as
compensation for Tenant's personal property, Trade Fixtures or Alterations.

     13.6  Waiver. Landlord and Tenant each hereby waive the provisions of
           ------
California Code of Civil Procedure Section 1265.130 and any other applicable
existing or future Law allowing either party to petition for a termination of
this Lease upon a partial taking of the Premises and/or the Property.

14.  ASSIGNMENT AND SUBLETTING.

     14.1  Landlord's Consent Required. Tenant shall not assign this Lease or
           ---------------------------
any interest therein, or sublet or license or permit the use or occupancy of the
Premises or any part thereof by or for the benefit of anyone other than Tenant,
or in any other manner transfer all or any part of Tenant's interest under this
Lease (each and all a "Transfer"), without the prior written consent of
Landlord, which consent (subject to the other provisions of this Section 14)
shall not be unreasonably withheld. If Tenant is a business entity, any direct
or indirect transfer of fifty percent (50%) or more of the ownership interest of
the entity (whether in a single transaction or in the aggregate through more
than one transaction) shall be deemed a Transfer. Notwithstanding any provision
in this Lease to the contrary, Tenant shall not mortgage, pledge, hypothecate or
otherwise encumber this Lease or all or any part of Tenant's interest under this
Lease.

     14.2  Reasonable Consent.
           ------------------

           (a) Prior to any proposed Transfer, Tenant shall submit in writing to
Landlord (i) the name and legal composition of the proposed assignee, subtenant,
user or other transferee (each a "Proposed Transferee"); (ii) the nature of the
business proposed to be carried on in the Premises; (iii) a current balance
sheet, income statements for the last two years and such other reasonable
financial and other information concerning the Proposed Transferee as Landlord
may request; and (iv) a copy of the proposed assignment, sublease or other
agreement governing the proposed Transfer. Within fifteen (15) Business Days
after Landlord receives all such information it shall notify Tenant whether it
approves or disapproves such Transfer or if it elects to proceed under Section
14.7 - Landlord's Right to Space.

           (b) Tenant acknowledges and agrees that, among other circumstances
for which Landlord could reasonably withhold consent to a proposed Transfer, it
shall be reasonable for Landlord to withhold consent where (i) the Proposed
Transferee does not intend itself to occupy the entire portion of the Premises
assigned or sublet, (ii) Landlord reasonably disapproves of the Proposed
Transferee's business operating ability or history, reputation or
creditworthiness or the character of the business to be conducted by the
Proposed Transferee at the Premises, (iii) the Proposed Transferee is a
governmental agency or unit or an existing tenant in the Project, (iv) the
proposed Transfer would violate any "exclusive" rights of any tenants in the
Project, (v) Landlord or Landlord's agent has shown space in the Building to the
Proposed Transferee or responded to any inquiries from the Proposed Transferee
or the Proposed Transferee's agent concerning

                                      -21-
<PAGE>

availability of space in the Building, at any time within the preceding nine
months, or (vi) Landlord otherwise determines that the proposed Transfer would
have the effect of decreasing the value of the Building or increasing the
expenses associated with operating, maintaining and repairing the Property. In
no event may Tenant publicly offer or advertise all or any portion of the
Premises for assignment or sublease at a rental less than that then sought by
Landlord for a direct lease (non- sublease) of comparable space in the Project.

     14.3  Excess Consideration If Landlord consents to the Transfer, Tenant
           --------------------
shall pay to Landlord as additional rent, within ten (10) days after receipt by
Tenant, any consideration paid by any transferee (the "Transferee") for the
Transfer, including, in the case of a sublease, the excess of the rent and other
consideration payable by the subtenant over the amount of Base Rent and
Additional Rent payable hereunder applicable to the subleased space.

     14.4  No Release Of Tenant.  No consent by Landlord to any Transfer shall
           --------------------
relieve Tenant of any obligation to be performed by Tenant under this Lease,
whether occurring before or after such consent, assignment, subletting or other
Transfer. Each Transferee shall be jointly and severally liable with Tenant (and
Tenant shall be jointly and severally liable with each Transferee) for the
payment of rent (or, in the case of a sublease, rent in the amount set forth in
the sublease) and for the performance of all other terms and provisions of this
Lease. The consent by Landlord to any Transfer shall not relieve Tenant or any
such Transferee from the obligation to obtain Landlord's express prior written
consent to any subsequent Transfer by Tenant or any Transferee. The acceptance
of rent by Landlord from any other person (whether or not such person is an
occupant of the Premises) shall not be deemed to be a waiver by Landlord of may
provision of this Lease or to be a consent to any Transfer.

     14.5  Expenses and Attorneys' Fees. Tenant shall pay to Landlord on demand
           ----------------------------
all costs and expenses (including reasonable attorneys' fees) incurred by
Landlord in connection with reviewing or consenting to any proposed Transfer
(including any request for consent to, or any waiver of Landlord's rights in
connection with, any security interest in any of Tenant's property at the
Premises).

     14.6  Effectiveness of Transfer. Prior to the date on which any permitted
           -------------------------
Transfer (whether or not requiring Landlord's consent) becomes effective, Tenant
shall deliver to Landlord a counterpart of the fully executed Transfer document
and Landlord's standard form of Consent to Assignment or Consent to Sublease
executed by Tenant and the Transferee in which each of Tenant and the Transferee
confirms its obligations pursuant to this Lease. Failure or refusal of a
Transferee to execute any such instrument shall not release or discharge the
Transferee from liability as provided herein. The voluntary, involuntary or
other surrender of this Lease by Tenant, or a mutual cancellation by Landlord
and Tenant, shall not work a merger, and any such surrender or cancellation
shall, at the option of Landlord, either terminate all or any existing subleases
or operate as an assignment to Landlord of any or all of such subleases.

     14.7  Landlord's Right to Space. Notwithstanding any of the above
           -------------------------
provisions of this Section to the contrary, if Tenant notifies Landlord that it
desires to enter into a Transfer, Landlord,

                                      -22-
<PAGE>

in lieu of consenting to such Transfer, may elect (x) in the case of an
assignment or a sublease of the entire Premises, to terminate this Lease, or (y)
in the case of a sublease of less than the entire Premises, to terminate this
Lease as it relates to the space proposed to be subleased by Tenant. In such
event, this Lease will terminate (or the space proposed to be subleased will be
removed from the Premises subject to this Lease and the Base Rent and Tenant's
Share under this Lease shall be proportionately reduced) on the earlier of sixty
(60) days after the date of Landlord's notice to Tenant making the election set
forth in this Section 14.7 or the date the Transfer was proposed to be
effective, and Landlord may lease such space to any party, including the
prospective Transferee identified by Tenant.

     14.8  Assignment of Sublease Rents. Tenant hereby absolutely and
           ----------------------------
irrevocably assigns to Landlord any and all rights to receive rent and other
consideration from any sublease and agrees that Landlord, as assignee or as
attorney-in-fact for Tenant for purposes hereof, or a receiver for Tenant
appointed on Landlord's application may (but shall not be obligated to) collect
such rents and other consideration and apply the same toward Tenant's
obligations to Landlord under this Lease; provided, however, that Landlord
grants to Tenant at all times prior to occurrence of any breach or default by
Tenant a revocable license to collect such rents (which license shall
automatically and without notice be and be deemed to have been revoked and
terminated immediately upon any Event of Default).

15.  DEFAULT AND REMEDIES.

     15.1  Events of Default The occurrence of any of the following shall
           -----------------
constitute an "Event of Default" by Tenant:

           (a)  Tenant fails to make any payment of rent when due, or any amount
required to replenish the security deposit as provided in Section 4 above, if
payment in full is not received by Landlord within three (3) days after written
notice that it is due.

           (b)  Tenant abandons the Premises.

           (c)  Tenant fails timely to deliver my subordination document,
estoppel certificate or financial statement requested by Landlord within the
applicable time period specified in Sections 20 - Encumbrances - and 21 -
Estoppel Certificates and Financial Statements - below.

          (d)   Tenant violates the restrictions on Transfer set forth in
Section 14 -Assignment and Subletting.

          (e)   Tenant ceases doing business as a going concern; makes an
assignment for the benefit of creditors; is adjudicated an insolvent, files a
petition (or files an answer admitting the material allegations of a petition)
seeking relief under any state or federal bankruptcy or other statute, law or
regulation affecting creditors' rights; all or substantially all of Tenant's
assets are subject to judicial seizure or attachment and are not released within
30 days, or Tenant consents to

                                      -23-
<PAGE>

or acquiesces in the appointment of a trustee, receiver or liquidator for Tenant
or for all or any substantial part of Tenant's assets.

           (f) Tenant fails, within ninety (90) days after the commencement of
any proceedings against Tenant seeking relief under any state or federal
bankruptcy or other statute, law or regulation affecting creditors' rights, to
have such proceedings dismissed, or Tenant fails, within ninety (90) days after
an appointment, without Tenant's consent or acquiescence, of any trustee,
receiver or liquidator for Tenant or for all or any substantial part of Tenant's
assets, to have such appointment vacated.

           (g) Tenant fails to perform or comply with any provision of this
Lease other than those described in (a) through (f) above, and does not fully
cure such failure within fifteen (15) days after notice to Tenant or, if such
failure cannot be cured within such fifteen (15)-day period, Tenant fails within
such fifteen (15)-day period to commence, and thereafter diligently proceed
with, all actions necessary to cure such failure as soon as reasonably possible
but in all events within ninety (90) days of such notice; provided, however,
that if Landlord in Landlord's reasonable judgment determines that such failure
cannot or will not be cured by Tenant within such ninety (90) days, then such
failure shall constitute an Event of Default immediately upon such notice to
Tenant.

     15.2  Remedies. Upon the occurrence of an Event of Default, Landlord shall
           --------
have the following remedies, which shall not be exclusive but shall be
cumulative and shall be in addition to any other remedies now or hereafter
allowed by law:

           (a) Landlord may terminate Tenant's right to possession of the
Premises at any time by written notice to Tenant. Tenant expressly acknowledges
that in the absence of such written notice from Landlord, no other act of
Landlord, including re-entry into the Premises, efforts to relet the Premises,
reletting of the Premises for Tenant's account, storage of Tenant's personal
property and Trade Fixtures, acceptance of keys to the Premises from Tenant or
exercise of any other rights and remedies under this Section, shall constitute
an acceptance of Tenant's surrender of the Premises or constitute a termination
of this Lease or of Tenant's right to possession of the Premises. Upon such
termination in writing of Tenant's right to possession of the Premises, as
herein provided, this Lease shall terminate and Landlord shall be entitled to
recover damages from Tenant as provided in California Civil Code Section 1951.2
and any other applicable existing or future Law providing for recovery of
damages for such breach, including the worth at the time of award of the amount
by which the rent which would be payable by Tenant hereunder for the remainder
of the Term after the date of the award of damages, including Additional Rent as
reasonably estimated by Landlord, exceeds the amount of such rental loss as
Tenant proves could have been reasonably avoided, discounted at the discount
rate published by the Federal Reserve Bank of San Francisco for member banks at
the time of the award plus one percent (1%).

           (b) Landlord shall have the remedy described in California Civil Code
Section 1951.4 (Landlord may continue this Lease in effect after Tenant's breach
and abandonment and

                                      -24-
<PAGE>

recover rent as it becomes due, if Tenant has the right to sublet or assign,
subject only to reasonable limitations).

           (c) Landlord may cure the Event of Default at Tenant's expense. If
Landlord pays any sum or incurs any expense in curing the Event of Default,
Tenant shall reimburse Landlord upon demand for the amount of such payment or
expense with interest at the Interest Rate from the date the sum is paid or the
expense is incurred until Landlord is reimbursed by Tenant.

           (d) Landlord may remove all Tenant's property from the Premises, and
such property may be stored by Landlord in a public warehouse or elsewhere at
the sole cost and for the account of Tenant. If Landlord does not elect to store
any or all of Tenant's property left in the Premises, Landlord may consider such
property to be abandoned by Tenant, and Landlord may thereupon dispose of such
property in any manner deemed appropriate by Landlord. Any proceeds realized by
Landlord on the disposal of any such property shall be applied first to offset
all expenses of storage and sale, then credited against Tenant's outstanding
obligations to Landlord under this Lease, and any balance remaining after
satisfaction of all obligations of Tenant under this Lease shall be delivered to
Tenant.

16.  LATE CHARGE AND INTEREST.

     16.1  Late Charge. If any payment of rent is not received by Landlord when
           -----------
due, Tenant shall pay to Landlord on demand as a late charge an additional
amount equal to four percent (4%) of the overdue payment. A late charge shall
not be imposed more than once on any particular installment not paid when due,
but imposition of a late charge on any payment not made when due does not
eliminate or supersede late charges imposed on other (prior) payments not made
when due or preclude imposition of a late charge on other installments or
payments not made when due.

     16.2  Interest. In addition to the late charges referred to above, which
           --------
are intended to defray Landlord's costs resulting from late payments, any
payment from Tenant to Landlord not paid when due shall at Landlord's option
bear interest from the date due until paid to Landlord by tenant at the rate of
fifteen percent (15%) per annum or the maximum lawful rate that Landlord may
charge to Tenant under applicable laws, whichever is less (the "Interest Rate").
Acceptance of any late charge and/or interest shall not constitute a waiver of
Tenant's default with respect to the overdue sum or prevent Landlord from
exercising any of its other rights and remedies under this Lease.

17.  WAIVER. No provisions of this Lease shall be deemed waived by Landlord
unless such waiver is in a writing signed by Landlord. The waiver by Landlord of
any breach of any provision of this Lease shall not be deemed a waiver of such
provision or of any subsequent breach of the same or any other provision of this
Lease. No delay or omission in the exercise of any right or remedy of Landlord
upon any default by Tenant shall impair such right or remedy or be construed as
a waiver. Landlord's acceptance of any payments of rent due under this Lease
shall not be deemed a waiver of any default by Tenant under this Lease
(including Tenant's recurrent failure to timely pay rent) other than Tenant's
nonpayment Of the accepted sums, and no endorsement or

                                      -25-
<PAGE>

statement on any check or payment or in any letter or document accompanying any
check or payment shall be deemed an accord and satisfaction. Landlord's consent
to or approval of any act by Tenant requiring Landlord's consent or approval
shall not be deemed to waive or render unnecessary Landlord's consent to or
approval of any subsequent act by Tenant.

18.  ENTRY, INSPECTION AND CLOSURE. Upon reasonable oral or written notice to
Tenant (and without notice in emergencies), Landlord and its authorized
representatives may enter the Premises at all reasonable times to: (a) determine
whether the Premises are in good condition, (b) determine whether Tenant is
complying with its obligations under this Lease, (c) perform any maintenance or
repair of the Premises or the Building that Landlord has the right or obligation
to perform, (d) install or repair improvements for other tenants where access to
the Premises is required for such installation or repair, (e) serve, post or
keep posted any notices required or allowed under the provisions of this Lease,
(f) show the Premises to prospective brokers, agents, buyers, transferees,
Mortgagees or tenants, or (g) do any other act or thing necessary for the safety
or preservation of the Premises or the Building. When reasonably necessary
Landlord may temporarily close entrances, doors, corridors, elevators or other
facilities in the Building without liability to Tenant by reason of such
closure. Landlord shall conduct its activities under this Section in a manner
that will minimize inconvenience to Tenant without incurring additional expense
to Landlord. In no event shall Tenant be entitled to an abatement of rent on
account of any entry by Landlord, and Landlord shall not be liable in any manner
for any inconvenience, loss of business or other damage to Tenant or other
persons arising out of Landlord's entry on the Premises in accordance with this
Section. No action by Landlord pursuant to this paragraph shall constitute an
eviction of Tenant, constructive or otherwise, entitle Tenant to an abatement of
rent or to terminate this Lease or otherwise release Tenant from any of Tenant's
obligations under this Lease.

19.  SURRENDER AND HOLDING OVER.

     19.1  Surrender. Upon the expiration or termination of this Lease, Tenant
           ---------
shall surrender the Premises and all Tenant Improvements and Alterations to
Landlord broom-clean and in their original condition, except for reasonable wear
and tear, damage from casualty or condemnation and any changes resulting from
approved Alterations; provided, however, that prior to the expiration or
termination of this Lease Tenant shall remove all telephone and other cabling
installed in the Building by Tenant and remove from the Premises all Tenant's
personal property and any Trade Fixtures and all Alterations that Landlord has
elected to require Tenant to remove as provided in Section 6.1 - Tenant
Improvements & Alterations, and repair any damage caused by such removal. If
such removal is not completed before the expiration or termination of the Term,
Landlord shall have the right (but no obligation) to remove the same, and Tenant
shall pay Landlord on demand for all costs of removal and storage thereof and
for the rental value of the Premises for the period from the end of the Term
through the end of the time reasonably required for such removal. Landlord shall
also have the right to retain or dispose of all or any portion of such property
if Tenant does not pay all such costs and retrieve the property within ten (10)
days after notice from Landlord (in which event title to all such property
described in Landlord's notice shall be transferred to and vest in Landlord).
Tenant waives all Claims against Landlord for any damage or loss to Tenant
resulting from Landlord's removal, storage, retention, or disposition of any
such

                                      -26-
<PAGE>

property. Upon expiration or termination of this Lease or of Tenant's
possession, whichever is earliest, Tenant shall surrender all keys to the
Premises or any other part of the Building and shall deliver to Landlord all
keys for or make known to Landlord the combination of locks on all safes,
cabinets and vaults that may be located in the Premises. Tenant's obligations
under this Section shall survive the expiration or termination of this Lease.

     19.2  Holding Over. If Tenant (directly or through any Transferee or other
           ------------
successor-in-interest of Tenant) remains in possession of the Premises after the
expiration or termination of this Lease, Tenant's continued possession shall be
on the basis of a tenancy at the sufferance of Landlord. No act or omission, by
Landlord, other than its specific written consent, shall constitute permission
for Tenant to continue in possession of the Premises, and if such consent is
given or declared to have been given by a court judgment, Landlord may terminate
Tenant's holdover tenancy at any time upon seven (7) days written notice. In
such event, Tenant shall continue to comply with or perform all the terms and
obligations of Tenant under this Lease, except that the monthly Base Rent during
Tenant's holding over shall be twice the Base Rent payable in the last full
month prior to the termination hereof. Acceptance by Landlord of rent after such
termination shall not constitute a renewal or extension of this Lease; and
nothing contained in this provision shall be deemed to waive Landlord's right of
re-entry or any other right hereunder or at law. Tenant shall indemnify, defend
and hold Landlord harmless from and against all Claims arising or resulting
directly or indirectly from Tenant's failure to timely surrender the Premises,
including (i) any rent payable by or any loss, cost, or damages claimed by any
prospective tenant of the Premises, and (ii) Landlord's damages as a result of
such prospective tenant rescinding or refusing to enter into the prospective
lease of the Premises by reason of such failure to timely surrender the
Premises.

20.  ENCUMBRANCES.

     20.1  Subordination This Lease is expressly made subject and subordinate to
           --------------
any mortgage, deed of trust, ground lease, underlying lease or like encumbrance
affecting any part of the Property or any interest of Landlord therein which is
now existing or hereafter executed or recorded ("Encumbrance"); provided,
however, that such subordination shall only be effective, as to future
Encumbrances, if the holder of the Encumbrance agrees that this Lease shall
survive the termination of the Encumbrance by lapse of time, foreclosure or
otherwise so long as Tenant is not in default under this Lease. Provided the
conditions of the preceding sentence are satisfied, Tenant shall execute and
deliver to Landlord, within ten (10) days after written request therefor by
Landlord and in a form reasonably requested by Landlord, any additional
documents evidencing the subordination of this Lease with respect to any such
Encumbrance and the nondisturbance agreement of the holder of any such
Encumbrance. If the interest of Landlord in the Property is transferred pursuant
to or in lieu of proceedings for enforcement of any Encumbrance, Tenant shall
immediately and automatically attorn to the new owner, and this Lease shall
continue in full force and effect as a direct lease between the transferee and
Tenant on the terms and conditions set forth in this Lease.

                                      -27-
<PAGE>

     20.2  Mortgagee Protection. Tenant agrees to give any holder of any
           --------------------
Encumbrance covering any part of the Property ("Mortgagee"), by registered mail,
a copy of any notice of default served upon Landlord, provided that prior to
such notice Tenant has been notified in writing (by way of notice of assignment
of rents and leases, or otherwise) of the address of such Mortgagee. If Landlord
shall have failed to cure such default within thirty (30) days from the
effective date of such notice of default, then the Mortgagee shall have an
additional thirty (30) days within which to cure such default or if such default
cannot be cured within that time, then such additional time as may be necessary
to cure such default (including the time necessary to foreclose or otherwise
terminate its Encumbrance, if necessary to effect such cure), and this Lease
shall not be terminated so long as such remedies are being diligently pursued.

21.  ESTOPPEL CERTIFICATES AND FINANCIAL STATEMENTS.

     21.1  Estoppel Certificates. Within ten (10) days after written request
           ---------------------
therefor, Tenant shall execute and deliver to Landlord, in a form provided by or
satisfactory to Landlord, a certificate stating that this Lease is in full force
and effect, describing any amendments or modifications hereto, acknowledging
that this Lease is subordinate or prior, as the case may be, to any Encumbrance
and stating any other information Landlord may reasonably request, including the
Term, the monthly Base Rent, the date to which Rent has been paid, the amount of
any security deposit or prepaid rent, whether either party hereto is in default
under the terms of the Lease, and whether Landlord has completed its
construction obligations hereunder (if any). Tenant irrevocably constitutes,
appoints and authorizes Landlord as Tenant's special attorney-in-fact for such
purpose to complete, execute and deliver such certificate if Tenant fails timely
to execute and deliver such certificate as provided above. Any person or entity
purchasing, acquiring an interest in or extending financing with respect to the
Property shall be entitled to rely upon any such certificate. If Tenant fails to
deliver such certificate within ten (10) days after Landlord's second written
request therefor, Tenant shall be liable to Landlord for any damages incurred by
Landlord including any profits or other benefits from any financing of the
Property or any interest therein which are lost or made unavailable as a result,
directly or indirectly, of Tenant's failure or refusal to timely execute or
deliver such estoppel certificate.

     21.2  Financial Statements. Within ten (10) days after written request
           --------------------
therefor, but not more than once a year, Tenant shall deliver to Landlord a copy
of the financial statements (including at least a year end balance sheet and a
statement of profit and loss) of Tenant (and of each guarantor of Tenant's
obligations under this Lease) for each of the three most recently completed
years, prepared in accordance with generally accepted accounting principles
(and, if such is Tenant's normal practice, audited by an independent certified
public accountant), all then available subsequent interim statements, and such
other financial information as may reasonably be requested by Landlord or
required by any Mortgagee.

22.  NOTICES. Any notice, demand, request, consent or approval that either party
desires or is required to give to the other party under this Lease shall be in
writing and shall be served personally, delivered by messenger or courier
service, or sent by U.S. certified mail, return receipt requested, postage
prepaid, addressed to the other party at the party's address for notices set
forth in

                                      -28-
<PAGE>

the Basic Lease Information. Any notice required pursuant to any Laws may be
incorporated into, given concurrently with or given separately from any notice
required under this Lease. Notices shall be deemed to have been given and be
effective on the earlier of (a) receipt (or refusal of delivery or receipt); or
(b) one (1) day after acceptance by the independent service for delivery, if
sent by independent messenger or courier service, or three (3) days after
mailing if sent by mail in accordance with this Section. Either party may change
its address for notices hereunder, effective fifteen (15) days after notice to
the other party complying with this Section. If Tenant sublets the Premises,
notices from Landlord shall be effective on the subtenant when given to Tenant
pursuant to this Section.

23.  ATTORNEYS' FEES. In the event of any dispute between Landlord and Tenant in
any way related to this Lease, and whether involving contract and/or tort
claims, the non-prevailing party shall pay to the prevailing party all
reasonable attorneys' fees and costs and expenses of any type, without
restriction by statute, court rule or otherwise, incurred by the prevailing
party in connection with any action or proceeding (including any appeal and the
enforcement of any judgment or award), whether or not the dispute is litigated
or prosecuted to final judgment (collectively, "Fees"). The "prevailing party"
shall be determined based upon an assessment of which party s major arguments or
positions taken in the action or proceeding could fairly be said to have
prevailed (whether by compromise, settlement, abandonment by the other party of
its claim or defense, final decision, after any appeals, or otherwise) over the
other party's major arguments or positions on major disputed issues. Any Fees
incurred in enforcing a judgment shall be recoverable separately from any other
amount included in the judgment and shall survive and not be merged in the
judgment. The Fees shall be deemed an "actual pecuniary loss" within the meaning
of Bankruptcy Code Section 365(b)(1)(B), and notwithstanding the foregoing, all
Fees incurred by either party in any bankruptcy case filed by or against the
other party, from and after the order for relief until this Lease is rejected or
assumed in such bankruptcy case, will be "obligations of the debtor" as that
phrase is used in Bankruptcy Code Section 365(d)(3).

24.  QUIET POSSESSION. Subject to Tenant's full and timely performance of all of
Tenant's obligations under this Lease and subject to the terms of this Lease,
including Section 20 -Encumbrances, Tenant shall have the quiet possession of
the Premises throughout the Term as against any persons or entities lawfully
claiming by, through or under Landlord.

25.  SECURITY MEASURES. Landlord may, but shall be under no obligation to,
implement security measures for the Property, such as the registration or search
of all persons entering or leaving the Building, requiring identification for
access to the Building, evacuation of the Building for cause, suspected cause,
or for drill purposes, the issuance of magnetic pass cards or keys for Building
or elevator access and other actions that Landlord deems necessary or
appropriate to prevent any threat of property loss or damage, bodily injury or
business interruption; provided, however, that such measures shall be
implemented in a way as not to inconvenience tenants of the Building
unreasonably. If Landlord uses an access card system, Landlord may require
Tenant to pay Landlord a deposit for each after-hours Building access card
issued to Tenant, in the amount specified in the Basic Lease Information. Tenant
shall be responsible for any loss, theft or

                                      -29-
<PAGE>

breakage of any such cards, which must be returned by Tenant to Landlord upon
expiration or earlier termination of the Lease. Landlord may retain the deposit
for any card not so returned. Landlord shall at all times have the right to
change, alter or reduce any such security services or. measures. Tenant shall
cooperate and comply with, and cause Tenant's Representatives and Visitors to
cooperate and comply with, such security measures. Landlord, its agents and
employees shall have no liability to Tenant or its Representatives or Visitors
for the implementation or exercise of, or the failure to implement or exercise,
any such security measures or for any resulting disturbance of Tenant's use or
enjoyment of the Premises.

26.  FORCE MAJEURE. If Landlord is delayed, interrupted or prevented from
performing any of its obligations under this Lease, including its obligations
under the Construction Rider (if any), and such delay, interruption or
prevention is due to fire, act of God, governmental act or failure to act, labor
dispute, unavailability of materials or any cause outside the reasonable control
of Landlord, then the time for performance of the affected obligations of
Landlord shall be extended for a period equivalent to the period of such delay,
interruption or prevention.

27.  RULES AND REGULATIONS. Tenant shall be bound by and shall comply with the
rules and regulations attached to and made a part of this Lease as Exhibit C to
                                                                   ---------
the extent those rules and regulations are not in conflict with the terms of
this Lease, as well as any reasonable rules and regulations hereafter adopted by
Landlord for all tenants of the Building, upon notice to Tenant thereof
(collectively, the "Building Rules"). Landlord shall not be responsible to
Tenant or to any other person for any violation of, or failure to observe, the
Building Rules by any other tenant or other person.

28.  LANDLORD'S LIABILITY. The term "Landlord," as used in this Lease, shall
mean only the owner or owners of the Building at the time in question. In the
event of any conveyance of title to the Building, then from and after the date
of such conveyance, the transferor Landlord shall be relieved of all liability
with respect to Landlord's obligations to be performed under this Lease after
the date of such conveyance. Notwithstanding any other term or provision of this
Lease, the liability of Landlord for its obligations under this Lease is limited
solely to Landlord's interest in the Building as the same may from time to time
be encumbered, and no personal liability shall at any time be asserted or
enforceable against any other assets of Landlord or against Landlord's partners
or members or its or their respective partners, shareholders, members,
directors, officers or managers on account of any of Landlord's obligations or
actions under this Lease.

29.  CONSENTS AND APPROVALS.

     29.1  Determination in Good Faith. Wherever the consent, approval, judgment
           ---------------------------
or determination of Landlord is required or permitted under this Lease, Landlord
may exercise its good faith business judgment in granting or withholding such
consent or approval or in making such judgment or determination without
reference to any extrinsic standard of reasonableness, unless the specific
provision contained in this Lease providing for such consent, approval, judgment
or determination specifies that Landlord's consent or approval is not to be
unreasonably withheld, or that such judgment or determination is to be
reasonable, or otherwise specifies the standards

                                      -30-
<PAGE>

under which Landlord may withhold its consent. If it is determined that Landlord
failed to give its consent where it was required to do so under this Lease,
Tenant shall be entitled to injunctive relief but shall not to be entitled to
monetary damages or to terminate this Lease for such failure.

     29.2  No Liability Imposed on Landlord. The review and/or approval by
           --------------------------------
Landlord of any item or matter to be reviewed or approved by Landlord under the
terms of this Lease or any Exhibits or Addenda hereto shall not impose upon
Landlord any liability for the accuracy or sufficiency of any such item or
matter or the quality or suitability of such item for its intended use. Any such
review or approval is for the sole purpose of protecting Landlord's interest in
the Property, and no third parties, including Tenant or the Representatives and
Visitors of Tenant or any person or entity claiming by, through or under Tenant,
shall have any rights as a consequence thereof.

30.  WAIVER OF RIGHT TO JURY TRIAL. Landlord and Tenant waive their respective
rights to trial by jury of any contract or tort claim, counterclaim, cross-
complaint, or cause of action in any action, proceeding, or hearing brought by
either party against the other on any matter arising out of or in any way
connected with this Lease, the relationship of Landlord and Tenant, or Tenant's
use or occupancy of the Premises, including any claim of injury or damage or the
enforcement of any remedy under any current or future law, statute, regulation,
code, or ordinance.

31.  BROKERS. Landlord shall pay the fee or commission of the broker or brokers
identified in the Basic Lease Information (the "Broker") in accordance with
Landlord's separate written agreement with the Broker, if any. Tenant warrants
and represents to Landlord that in the negotiating or making of this Lease
neither Tenant nor anyone acting on Tenant's behalf has dealt with any broker or
finder who might be entitled to a fee or commission for this Lease other than
the Broker. Tenant shall indemnify and hold Landlord harmless from any claim or
claims, including costs, expenses and attorney's fees incurred by Landlord
asserted by rely other broker or finder for a fee or commission based upon any
dealings with or statements made by Tenant or Tenant's Representatives.

32.  RELOCATION OF PREMISES. For the purpose of maintaining an economical and
proper distribution of tenants acceptable to Landlord throughout the Project,
Landlord shall have the right from time to time during the Term to relocate the
Premises within the Project, provided that (a) the rentable and usable area of
the new Premises is of equivalent size to the existing Premises, subject to a
variation of up to ten percent (10%), (b) Landlord shall pay the cost of
providing tenant improvements in the new Premises, which shall be substantially
comparable in layout to those in the existing Premises, (c) Landlord shall pay
reasonable costs (to the extent such costs are submitted in writing to Landlord
and approved in writing by Landlord prior to such move) of moving Tenant's Trade
Fixtures and personal property to the new Premises, and (d) Landlord shall pay
reasonable costs (to the extent such costs are submitted in writing to Landlord
and approved in writing by Landlord prior to such move) of reprinting Tenant's
letterhead and marketing materials to reference the new address, which costs
Landlord acknowledges could exceed fifty thousand dollars ($50,000). Landlord
shall deliver to Tenant written notice of

                                      -31-
<PAGE>

Landlord's election to relocate the Premises, specifying the new location and
the amount of rent payable therefor, at least sixty (60) days prior to the date
the relocation is to be effective.

33.  ENTIRE AGREEMENT. This Lease, including the Exhibits and any Addenda
attached hereto, and the documents referred to herein, if may, constitute the
entire agreement between Landlord and Tenant with respect to the leasing of
space by Tenant in the Building, and supersede all prior or contemporaneous
agreements, understandings, proposals and other representations by or between
Landlord and Tenant, whether written or oral, all of which are merged herein.
Neither Landlord nor Landlord's agents have made any representations or
warranties with respect to the Premises, the Building, the Project or this Lease
except as expressly set forth herein, and no rights, easements or licenses shall
be acquired by Tenant by implication or otherwise unless expressly set forth
herein. The submission of this Lease for examination does not constitute an
option for the Premises and this Lease shall become effective as a binding
agreement only upon execution and delivery thereof by Landlord to Tenant.

34.  MISCELLANEOUS. This Lease may not be amended or modified except by a
writing signed by Landlord and Tenant. Subject to Section 14 - Assignment and
Subletting and Section 28 - Landlord's Liability, this Lease shall be binding
on and shall inure to the benefit of the parties and their respective
successors, assigns and legal representatives. The determination that any
provisions hereof may be void, invalid, illegal or unenforceable shall not
impair any other provisions hereof and all such other provisions of this Lease
shall remain in full force and effect. The unenforceability, invalidity or
illegality of any provision of this Lease under particular circumstances shall
not render unenforceable, invalid or illegal other provisions of this Lease, or
the same provisions under other circumstances. This Lease shall be construed and
interpreted in accordance with the laws (excluding conflict of laws principles)
of the State in which the Building is located. The provisions of this Lease
shall be construed in accordance with the fair meaning of the language used and
shall not be strictly construed against either party, even if such party drafted
the provision in question. When required by the context of this Lease, the
singular includes the plural. Wherever the term "including" is used in this
Lease, it shall be interpreted as meaning "including, but not limited to" the
matter or matters thereafter enumerated. The captions contained in this Lease
are for purposes of convenience only and are not to be used to interpret or
construe this Lease. If more than one person or entity is identified as Tenant
hereunder, the obligations of each and all of them under this Lease shall be
joint and several. Time is of the essence with respect to this Lease, except as
to the conditions relating to the delivery of possession of the Premises to
Tenant. Neither Landlord nor Tenant shall record this Lease.

35.  AUTHORITY. If Tenant is a corporation, partnership, limited liability
company or other form of business entity, each of the persons executing this
Lease on behalf of Tenant warrants and represents that Tenant is a duly
organized and validly existing entity, that Tenant has full right and authority
to enter into this Lease and that the persons signing on behalf of Tenant are
authorized to do so and have the power to bind Tenant to this Lease. Tenant
shall provide Landlord upon request with evidence reasonably satisfactory to
Landlord confirming the foregoing representations.

                                      -32-
<PAGE>

     IN WITNESS WHEREOF, Landlord and Tenant have entered into this Lease as of
the date first above written.


TENANT:                                 LANDLORD:

TRINTECH, INC.,                         PENINSULA OFFICE PARK
                                        ASSOCIATES, L.P.,
a California corporation                a California limited partnership


By: /s/ John McGuire                    By:   CORNERSTONE HOLDINGS, LLC,
   ----------------------------
Name: John McGuire                            a Delaware limited liability
     --------------------------
Title:   CEO                                  company General Partner
      -------------------------

                                        By:  /s/ [ILLEGIBLE]^^
                                           ----------------------------
By: ___________________________         Name: /s/ [ILLEGIBLE]^^
                                             --------------------------
Name: _________________________         Title: [ILLEGIBLE]^^
                                              -------------------------
Title: ________________________

                                      -33-
<PAGE>

                                   EXHIBIT A
                                   ---------

                       ATTACHED TO AND FORMING A PART OF
                                LEASE AGREEMENT
                           DATED AS OF MAY 28, 1999
                                    BETWEEN
             PENINSULA OFFICE PARK ASSOCIATES, L.P., AS LANDLORD,
                                      AND
                      TRINTECH, INC., AS TENANT ("LEASE")


                                 THE PREMISES
                                 ------------



                                 [FLOOR PLAN]



           Peninsula Office Park - 2755 Campus Drive, San Mateo, CA



                                                   INITIALS:

                                                   Landlord /s/ [ILLEGIBLE]^^
                                                            -----------------
                                                   Tenant   /s/ [ILLEGIBLE]^^
                                                            -----------------

                               Exhibit A, Page 1
<PAGE>

                                   EXHIBIT B
                                   ---------

                       ATTACHED TO AND FORMING A PART OF
                                LEASE AGREEMENT
                           DATED AS OF MAY 28, 1999
                                    BETWEEN
             PENINSULA OFFICE PARK ASSOCIATES, L.P., AS LANDLORD,
                                      AND
                      TRINTECH, INC., AS TENANT ("LEASE")

                              CONSTRUCTION RIDER
                              ------------------

1.  Tenant Improvements. Tenant shall take the Premises in their existing "AS
    -------------------
IS" condition without any work to be done thereto by Landlord. Tenant may, using
Commercial Interior Contractors ("CIC") construct and install in the Premises
the improvements and fixtures provided for in this Construction Rider ("Tenant
Improvements") at Tenant's sole cost and expense, subject to the Allowance as
hereinafter provided, in accordance with the provisions of Section 6.1 of the
Lease - Alterations. Tenant acknowledges and agrees that CIC is an affiliate of
Landlord.

          1.2. Plans for Tenant Improvements and Substantial Completion. At
               --------------------------------------------------------
least ten (10) days prior to the date Tenant intends to commence construction of
the Tenant Improvements, Tenant shall submit to Landlord, for Landlord's
approval, proposed plans for the Tenant Improvements. The plans approved by.
Landlord, which approval shall not be unreasonably withheld, are called the
"Approved Plans." CIC shall construct the Tenant Improvements in accordance with
the Approved Plans. The Tenant Improvements shall be deemed to be "Substantially
Completed" when they have been completed in accordance with the Approved Plans
except for finishing details, minor omissions, decorations and mechanical
adjustments of the type normally found on an architectural "punch list". (The
definition of Substantially Completed shall also define the terms "Substantial
Completion" and "Substantially Complete.")

          1.3. Cost of Tenant Improvements. Landlord shall contribute up to
               ---------------------------
$5.00 per rentable square foot in the Premises (the "Allowance") toward the cost
of the Tenant Improvements. Landlord shall pay the Allowance to CIC upon
completion of the Tenant Improvements, and evidence that no construction liens
will be filed against the Property. The balance, if any, of the cost of the
Tenant Improvements ("Additional Cost"), including, but not limited to, usual
markups for overhead, supervision and profit, shall be paid by Tenant. Tenant
shall pay to CIC 50% of the Additional Cost prior to the commencement of
construction of the Tenant Improvements. The balance, if any, of the cost of the
Tenant Improvements ("Additional Cost") shall be paid by Tenant directly to CIC
upon completion of the Tenant Improvements. Tenant's failure to pay the
Additional Cost to CIC within ten (10) days after

                               Exhibit B, Page 1
<PAGE>

written notice from Landlord shall constitute an Event of Default under the
Lease without any requirement for Landlord to give any additional notice to
Tenant.

         1.4.  Changes.
               -------

         1.5.  Delays.
               ------

     2.  Delivery of Premises. Landlord shall deliver possession of the Premises
         --------------------
to Tenant after Landlord has obtained possession of the Premises from the
Existing Tenant following complete execution of this Lease.

     3.  Access to Premises. Landlord shall allow Tenant and Tenant's
         ------------------
Representatives to enter the Premises prior to the Commencement Date to permit
Tenant to make the Premises ready for its use and occupancy; provided, however,
that prior to such entry of the Premises, Tenant shall provide evidence
reasonably satisfactory to Landlord that Tenant's insurance, as described in
Section 11.1 - Tenant's Insurance of the Lease, shall be in effect as of the
time of such entry.

     Tenant agrees that Landlord shall not be liable in any way for any injury,
loss or damage which may occur to any of Tenant's property placed upon or
installed in the Premises prior to the Commencement Date, the same being at
Tenant's sole risk, and Tenant shall be liable for all injury, loss or damage to
persons or property arising as a result of such entry into the Premises by
Tenant or its Representatives.

     4.  Ownership of Tenant Improvements. All Tenant Improvements, whether
         --------------------------------
installed by Landlord or Tenant, shall become a part of the Premises, shall be
the property of Landlord and, subject to the provisions of the Lease, shall be
surrendered by Tenant with the Premises, without any compensation to Tenant, at
the expiration or termination of the Lease in accordance with the provisions of
the Lease.



                                                   INITIALS:

                                                   Landlord  /s/ [ILLEGIBLE]^^
                                                             -----------------
                                                   Tenant    /s/ [ILLEGIBLE]^^
                                                             -----------------
                               Exhibit B, Page 2
<PAGE>

                                   EXHIBIT C
                                   ---------

                       ATTACHED TO AND FORMING A PART OF
                                LEASE AGREEMENT
                           DATED AS OF MAY 28, 1999
                                    BETWEEN
             PENINSULA OFFICE PARK ASSOCIATES, L.P., AS LANDLORD,
                                      AND
                      TRINTECH, INC., AS TENANT ("LEASE")

                                BUILDING RULES
                                --------------

     The following Building Rules are additional provisions of the foregoing
Lease to which they are attached. The capitalized terms used herein have the
same meanings as these terms are given in the Lease.

     1.  Use of Common Areas. Tenant will not obstruct the sidewalks, halls,
         -------------------
passages, exits, entrances, elevators or stairways of the Building ("Common
Areas"), and Tenant will not use the Common Areas for any purpose other than
ingress and egress to and from the Premises. The Common Areas, except for the
sidewalks, are not open to the general public and Landlord reserves the right to
control and prevent access to the Common Areas of any person whose presence, in
Landlord's opinion, would be prejudicial to the safety, reputation and interests
of the Building and its tenants.

     2.  No Access to Roof. Tenant has no right of access to the roof of the
         -----------------
Building and will not install, repair or replace any antenna, aerial, aerial
wires, fan, air-conditioner or other device on the roof of the Building, without
the prior written consent of Landlord. Any such device installed without such
written consent is subject to removal at Tenant's expense without notice at any
time. In any event Tenant will be liable for any damages or repairs incurred or
required as a result of its installation, use, repair, maintenance or removal of
such devices on the roof and agrees to indemnify and hold harmless Landlord from
any liability, loss, damage, cost or expense, including reasonable attorneys'
fees, arising from any activities of Tenant or of Tenant's Representatives on
the roof of the Building.

     3.  Signage. No sign, placard, picture, name, advertisement or notice
         -------
visible from the exterior of the Premises will be inscribed, painted, affixed or
otherwise displayed by Tenant on or in any part of the Building without the
prior written consent of Landlord. Landlord reserves the right to adopt and
furnish Tenant with general guidelines relating to signs in or on the Building.
All approved signage will be inscribed, painted or affixed at Tenant's expense
by a person approved by Landlord, which approval will not be unreasonably
withheld.

                               Exhibit C, Page 1
<PAGE>

     4.  Prohibited Uses. The Premises will not be used for manufacturing, for
         ---------------
the storage of merchandise held for sale to the general public, for lodging or
for the sale of goods to the general public. Tenant will not permit any food
preparation on the Premises except that Tenant may use Underwriters' Laboratory
approved equipment for brewing coffee, tea, hot chocolate and similar beverages
so long as such use is in accordance with all applicable federal, state and city
laws, codes, ordinances, rules and regulations.

     5.  Janitorial Services. Tenant will not employ any person for the purpose
         -------------------
of cleaning the Premises or permit any person to enter the Building for such
purpose other than Landlord's janitorial service, except with Landlord's prior
written consent. Tenant will not necessitate, and will be liable for the cost
of, any undue amount of janitorial labor by reason of Tenant's carelessness in
or indifference to the preservation of good order and cleanliness in the
Premises. Janitorial service will not be furnished to areas in the Premises on
nights when such areas are occupied after 9:30 p.m., unless such service is
extended by written agreement to a later hour in specifically designated areas
of the Premises.

     6.  Keys and Locks. Landlord will furnish Tenant, free of charge, two keys
         --------------
to each door or lock in the Premises. Landlord may make a reasonable charge for
any additional or replacement keys. Tenant will not duplicate any keys, alter
any locks or install any new or additional lock or bolt on any door of its
Premises or on any other part of the Building without the prior written consent
of Landlord and, in any event, Tenant will provide Landlord with a key for any
such lock. On the termination of the Lease, Tenant will deliver to Landlord all
keys to any locks or doors in the Building which have been obtained by Tenant.

     7.  Freight. Upon not less than twenty-four hours prior notice to Landlord,
         -------
which notice may be oral, an elevator will be made available for Tenant's use
for transportation of freight, subject to such scheduling as Landlord in its
discretion deems appropriate. Tenant shall not transport freight in loads
exceeding the weight limitations of such elevator. Landlord reserves the right
to prescribe the weight, size and position of all equipment, materials,
furniture or other property brought into the Building, and no property will be
received in the Building or carried up or down the freight elevator or stairs
except during such hours and along such routes and by such persons as may be
designated by Landlord. Landlord reserves the right to require that heavy
objects will stand on wood strips of such length and thickness as is necessary
to properly distribute the weight. Landlord will not be responsible for loss of
or damage to any such property from any cause, and Tenant will be liable for all
damage or injuries caused by moving or maintaining such property.

     8.  Nuisances and Dangerous Substances. Tenant will not conduct itself or
         ----------------------------------
permit Tenant's Representatives or Visitors to conduct themselves, in the
Premises or anywhere on or in the Property in a manner which is offensive or
unduly annoying to any other Tenant or Landlord's property managers. Tenant will
not install or operate any phonograph, radio receiver, musical instrument, or
television or other similar device in any part of the Common Areas and shall not
operate any such device installed in the Premises in such manner as to disturb
or annoy other tenants Of the Building. Tenant will not use or keep in the
Premises or the Property any

                               Exhibit C, Page 2
<PAGE>

kerosene, gasoline or other combustible fluid or material other than limited
quantities thereof reasonably necessary for the maintenance of office equipment,
or, without Landlord's prior written approval, use any method of heating or air
conditioning other than that supplied by Landlord. Tenant will not use or keep
any foul or noxious gas or substance in the Premises or permit or suffer the
Premises to be occupied or used in a manner offensive or objectionable to
Landlord or other occupants of the Building by reason of noise, odors or
vibrations, or interfere in any way with other tenants or those having business
therein. Tenant will not bring or keep any animals in or about the Premises or
the Property.

     9.   Building Name and Address. Without Landlord's prior written consent,
          -------------------------
Tenant will not use the name of the Building in connection with or in promoting
or advertising Tenant's business except as Tenant's address.

     10.  Building Directory. A directory for the Building will be provided for
          ------------------
the display of the name and location of tenants. Landlord reserves the right to
approve any additional names Tenant desires to place in the directory and, if so
approved, Landlord may assess a reasonable charge for adding such additional
names.

     11.  Window Coverings. No curtains, draperies, blinds, shutters, shades,
          ----------------
awnings, screens or other coverings, window ventilators, hangings, decorations
or similar equipment shall be attached to, hung or placed in, or used in or with
any window of the Building without the prior written consent of Landlord, and
Landlord shall have the right to control all lighting within the Premises that
may be visible from the exterior of the Building.

     12.  Floor Coverings. Tenant will not lay or otherwise affix linoleum,
          ---------------
tile, carpet or any other floor covering to the floor of the Premises in any
manner except as approved in writing by Landlord. Tenant will be liable for the
cost of repair of any damage resulting from the violation of this rule or the
removal of any floor covering by Tenant or its contractors, employees or
invitees.

     13.  Wiring and Cabling Installations. Landlord will direct Tenant's
          --------------------------------
electricians and other vendors as to where and how data, telephone, and
electrical wires and cables are to be installed. No boring or cutting for wires
or cables will be allowed without the prior written consent of Landlord. The
location of burglar alarms smoke detectors, telephones, call boxes and other
office equipment affixed to the Premises shall be subject to the written
approval of Landlord.

     14.  Office Closing Procedures. Tenant will see that the doors of the
          -------------------------
Premises are closed and locked and that all water faucets, water apparatus and
utilities are shut off before Tenant or its employees leave the Premises, so as
to prevent waste or damage. Tenant will be liable for all damage or injuries
sustained by other tenants or occupants of the Building or Landlord resulting
from Tenant's carelessness in this regard or violation of this rule. Tenant will
keep the doors to the Building corridors closed at all times except for ingress
and egress.

                               Exhibit C, Page 3
<PAGE>

     15.  Plumbing Facilities. The toilet rooms, toilets, urinals, wash bowls
          -------------------
and other apparatus shall not be used for any purpose other than that for which
they were constructed and no foreign substance of any kind whatsoever shall be
disposed of therein. Tenant will be liable for any breakage, stoppage or damage
resulting from the violation of this rule by Tenant, its employees or invitees.

     16.  Use of Hand Trucks. Tenant will not use or permit to be used in the
          ------------------
Premises or in the Common Areas any hand trucks, carts or dollies except those
equipped with rubber tires and side guards or such other equipment as Landlord
may approve.

     17.  Refuse. Tenant shall store all Tenant's trash and garbage within the
          ------
Premises or in other facilities designated By Landlord for such purpose. Tenant
shall not place in any trash box or receptacle any material which cannot be
disposed of in the ordinary and customary manner of removing and disposing of
trash and garbage in the city in which the Building is located without being in
violation of any law or ordinance governing such disposal. All trash and garbage
removal shall be made in accordance with directions issued from time to time by
Landlord, only through such Common Areas provided for such purposes and at such
times as Landlord may designate. Tenant shall comply with the requirements of
any recycling program adopted by Landlord for the Building.

     18.  Soliciting. Canvassing, peddling, soliciting and distribution of
          ----------
handbills or any other written materials in the Building are prohibited, and
Tenant will cooperate to prevent the same.

     19.  Parking. Tenant will use, and cause Tenant's Representatives and
          -------
Visitors to use, any parking spaces to which Tenant is entitled under the Lease
in a manner consistent with Landlord's directional signs and markings in the
Parking Facility. Specifically, but without limitation, Tenant will not park, or
permit Tenant's Representatives or Visitors to park, in a manner that impedes
access to and from the Building or the Parking Facility or that violates space
reservations for handicapped drivers registered as such with the California
Department of Motor Vehicles. Landlord may use such reasonable means as may be
necessary to enforce the directional signs and markings in the Parking Facility,
including but not limited to towing services, and Landlord will not be liable
for any damage to vehicles towed as a result of non-compliance with such parking
regulations.

     20.  Fire, Security and Safety Regulations. Tenant will comply with all
          -------------------------------------
safety, security, fire protection and evacuation measures and procedures
established by Landlord or any governmental agency.

     21.  Responsibility for Theft. Tenant assumes any and all responsibility
          ------------------------
for protecting the Premises from theft, robbery and pilferage, which includes
keeping doors locked and other means of entry to the Premises closed.

                               Exhibit C, Page 4
<PAGE>

     22.  Sales and Auctions. Tenant will not conduct or permit to be conducted
          ------------------
any sale by auction in, upon or from the Premises or elsewhere in flee Property,
whether said auction be voluntary, involuntary, pursuant to any assignment for
the payment of creditors or pursuant to any bankruptcy or other insolvency
proceeding.

     23.  Waiver of Rules. Landlord may waive any one or more of these Building
          ---------------
Rules for the benefit of any particular tenant or tenants, but no such waiver by
Landlord will be construed as a waiver of such Building Rules in favor of any
other tenant or tenants nor prevent Landlord from thereafter enforcing these
Building Rules against any or all of the tenants of the Building.

     24.  Effect on Lease. These Building Rules are in addition to, and shall
          ---------------
not be construed to in any way modify or amend, in whole or in part, the terms,
covenants, agreements and conditions of the Lease. Violation of these Building
Rules constitutes a failure to fully perform the provisions of the Lease, as
referred to in Section 15.1 - "Events of Default".

     25.  Non-Discriminatory Enforcement. Subject to the provisions of the Lease
          ------------------------------
(and the provisions of other leases with respect to other tenants), Landlord
shall use reasonable efforts to enforce these Building Rules in a non-
discriminatory manner, but in no event shall Landlord. have any liability for
any failure or refusal to do so (and Tenant's sole and exclusive remedy for any
such failure or refusal shall be injunctive relief preventing Landlord from
enforcing any of the Building Rules against Tenant in a manner that
discriminates against Tenant).

     26.  Additional and Amended Rules. Landlord reserves the right to rescind
          ----------------------------
or amend these Building Rules and/or adopt any other and reasonable rules and
regulations as in its judgment may from time to time be needed for the safety,
care and cleanliness of the Building and for the preservation of good order
therein.



                                                   INITIALS:

                                                   Landlord  /s/ [ILLEGIBLE]^^
                                                             -----------------
                                                   Tenant    /s/ [ILLEGIBLE]^^
                                                             -----------------

                               Exhibit C, Page 5
<PAGE>

                                   EXHIBIT D
                                   ---------

                       ATTACHED TO AND FORMING A PART OF
                                LEASE AGREEMENT
                           DATED AS OF MAY 28, I999
                                    BETWEEN
             PENINSULA OFFICE PARK ASSOCIATES, L.P., AS LANDLORD,
                                      AND
                      TRINTECH, INC., AS TENANT ("LEASE")

                          ADDITIONAL PROVISIONS RIDER
                          ---------------------------

36.  LETTER OF CREDIT.
     ----------------

     (a) Upon execution of this Lease, Tenant shall deliver to Landlord an
unconditional, irrevocable, transferable and negotiable standby letter of credit
(the "L/C") in an amount equal to $161,313.00 ("Face Amount"), issued by a bank
or trust company ("Issuer") and in form and content acceptable to Landlord, in
its sole and absolute discretion, as additional security for the performance of
Tenant's obligations under this Lease. An L/C in the form attached hereto as
Exhibit E is hereby approved by Landlord. The L/C shall name Landlord as
---------
beneficiary thereunder and provide that draws, including partial draws, at
Landlord's election, will be honored upon the delivery to the Issuer of a
certificate signed by. Landlord, or its authorized agent, that Tenant has failed
to perform its obligations under the Lease. The L/C shall also provide that it
will be automatically extended upon each renewal date unless the Issuer thereof
delivers to Landlord, no later than forty-five (45) days prior to the stated
expiration date of the L/C, written notice of Issuer's intent not to extend or
renew the L/C. During any period that Tenant is required to maintain the L/C,
Tenant shall, at least thirty (30) days prior to any expiration or termination
of the L/C, provide Landlord either with written confirmation that the existing
L/C will be automatically extended and renewed or with a new L/C that satisfies
all of the requirements for the L/C in this Section 36. In addition, upon a
proposed sale or other transfer of any interest in the Building, the Land, this
Lease or Landlord (including consolidations, mergers, or other entity changes),
Tenant, at its sole cost and expense and upon ten (10) Business Days' notice,
shall, concurrent with Landlord's delivery to Tenant of the then outstanding
L/C, deliver to any such transferees, successors, or assigns a replacement L/C
on identical terms (except for the stated beneficiary) from the same Issuer or
another bank or trust company acceptable to Landlord, in Landlord's sole
discretion, naming the new landlord as the beneficiary thereof. Tenant's failure
to perform or observe any of the covenants set forth in this Section 36 for any
reason shall entitle Landlord to draw on the full amount of the L/C and shall
constitute an Event of Default under this Lease without the requirement of any
notice from Landlord. Any amount(s) drawn under the L/C shall be held or used by
Landlord in accordance with the terms of Section 4 of the Lease. If Landlord
draws on the L/C, then upon Tenant curing the covenant which entitled Landlord
to draw on the L/C, Tenant shall have the right, upon ten (10) days prior
written notice to Landlord, to obtain a refund from Landlord of any unapplied
proceeds of the L/C Which Landlord has drawn upon, any such

                               Exhibit D, Page 1
<PAGE>

refund being conditioned upon Tenant simultaneously delivering to Landlord a
new, replacement L/C in the amount required hereinabove, and meeting the
requirements contained herein. If Landlord has applied a portion of the L/C
which Landlord has drawn upon toward the payment or performance of Tenant's
obligations under the Lease, then the amount of the refund from Landlord to
Tenant pursuant to the provisions of fills paragraph will be less than the
amount of the replacement L/C.

     (b) If as of the second (2nd), third (3rd) and fourth (4th) anniversary
dates following the Commencement Date, no prior or current Event of Default has
occurred, and no event or condition exists or has occurred which with the
passage of time or delivery of notice by Landlord, or both, would constitute an
Event of Default, the Face Amount of the L/C may be immediately reduced to
$120,985 on the second (2nd) anniversary date following the Commencement Date,
to $80,657.00 on third (3rd) anniversary date following the Commencement Date,
and to $40,329.00 on the fourth (4th) anniversary date following the
Commencement Date, as applicable (the "L/C Burnoff").

37.  PARKING.

     (a) Tenant's Parking Rights. Landlord shall provide Tenant, on an
         -----------------------
unassigned and non-exclusive basis, for use by Tenant and Tenant's
Representatives and Visitors, at the users' sole risk, twenty-four (24) parking
spaces in the Parking Facility. If Tenant leases additional office space
pursuant to this Lease, Landlord shall provide Tenant, also on an unassigned,
non-exclusive and unlabelled basis, three and one-third (3.3) additional parking
spaces in the Parking Facility for each one thousand (1,000) rentable square
feet of additional office space leased to Tenant. The parking spaces to be made
available to Tenant hereunder may contain a reasonable mix of spaces for compact
cars and up to ten percent (10%) of the unassigned spaces may also be designated
by Landlord as Building visitors' parking.

     (b) Availability of Parking Spaces. Landlord shall take reasonable actions
         ------------------------------
to ensure the availability of the parking spaces leased by Tenant, but Landlord
does not guarantee the availability of those spaces at all times against the
actions of other tenants of the Building and users of the Parking Facility.
Access to the Parking Facility may, at Landlord's option, be regulated by card,
pass, bumper sticker, decal or other appropriate identification issued by
Landlord. Landlord retains the right to revoke the parking privileges of any
user of the Parking Facility who violates the rules and regulations governing
use of the Parking Facility (and Tenant shall be responsible for causing any
employee of Tenant or other person using parking spaces allocated to Tenant to
comply with all parking rules and regulations).

     (c) Assignment and Subletting. Notwithstanding any other provision of the
         -------------------------
Lease to the contrary, Tenant shall not assign its rights to the parking spaces
or any interest therein, or sublease or otherwise allow the use of all or any
part of the parking spaces to or by any other person, except (i) to a
Transferee, or (ii) with Landlord's prior written consent, which may be granted
or withheld by Landlord in its sole discretion. In the event of any separate
assignment or sublease of parking space rights that is approved by Landlord,
Landlord shall be entitled to

                               Exhibit D, Page 2
<PAGE>

receive, as additional Rent hereunder, one hundred percent (100%) of any profit
received by Tenant in connection with such assignment or sublease.

     (d) Condemnation, Damage or, Destruction. In the event the Parking Facility
         ------------------------------------
is the subject of a Condemnation, or is damaged or destroyed, and this Lease is
not terminated, and if in such event the available number of parking spaces in
the Parking Facility is permanently reduced, then Tenant's rights to use parking
spaces hereunder may, at the election of Landlord, thereafter be reduced in
proportion to the reduction of the total number of parking spaces in the Parking
Facility, and the Monthly Parking Rental payable hereunder shall be reduced
proportionately. In such event, Landlord reserves the right to reduce the number
of parking spaces to which Tenant is entitled or to relocate some or all of the
parking spaces to which Tenant is entitled to other areas in the Parking
Facility.



                                                   INITIALS:

                                                   Landlord  /s/ [ILLEGIBLE]^^
                                                             -----------------
                                                   Tenant    /s/ [ILLEGIBLE]^^
                                                             -----------------

                               Exhibit D, Page 3
<PAGE>

                                   EXHIBIT E
                                   ---------

                       ATTACHED TO AND FORMING A PART OF
                                LEASE AGREEMENT
                           DATED AS OF MAY 28, 1999
                                    BETWEEN
             PENINSULA OFFICE PARK ASSOCIATES, L.P., AS LANDLORD,
                                      AND
                      TRINTECH, INC., AS TENANT ("LEASE")

                        APPROVED LETTER OF CREDIT FORM
                        ------------------------------

[Letterhead of Issuing Bank]
[must be a Bank whose location, credit and practices Landlord has approved]

RE:  IRREVOCABLE COMMERCIAL LETTER OF CREDIT NO. _________

TO:  [Name of project owner] ("Landlord"),  ___________________________________
___________________ [Landlord's address]

Gentlemen:

We hereby issue our Irrevocable Commercial Letter of Credit in your favor, for
the account of _______________________ [name of tenant and type of entity (e.g.
"ABC Corporation, a California corporation")] ("Tenant"), in the amount of
_________________________ Dollars ($________). This amount is available to you
on presentation of your sight draft drawn upon us referring to the above letter
of credit number, date and amount being drawn hereunder, accompanied by the
signed statement of you or your authorized agent, Cornerstone Properties Limited
Partnership dba Wilson Cornerstone Properties Limited Partnership, that the
amount drawn hereunder is being drawn pursuant to the terms of the ____________
[title of lease document (e.g. Office Lease, Lease Agreement, etc.)] dated as of
_____________, between Tenant, as tenant, and Landlord, as landlord, for certain
premises located at __________________

____________________________ (the "Lease").

Any draft presented for payment must be presented on or before ___________ [term
should be at least one year], the date this Letter of Credit expires. Partial
drawings are permitted.

If you sell or otherwise transfer any interest in the "Building" (as defined in
the Lease) [be sure to use the defined terms used in the Lease (e.g. if the
building is called the "Property" in the Lease, then use that term here)], in
the land upon which the same is located, in the Lease, or in

                               Exhibit E, Page 1
<PAGE>

Landlord (including consolidations, mergers or other entity changes), you shall
have the right to transfer this Letter of Credit to your transferee(s),
successors or assigns.

We hereby certify that this is an unconditional and irrevocable Letter of Credit
and agree that a draft drawn under and in compliance with the terms hereof will
be honored upon presentation at our office at ________________________ [it must
be a location easily accessible to us (e.g. no country banks located in some
tiny town in the Southeastern corner of Texas].

This Letter of Credit shall automatically be extended and renewed for successive
one year periods at the end of the stated expiration date and each anniversary
thereof unless we notify you in writing, no later than forty-five (45) days
prior to the then applicable expiration date, that we will not extend and renew
the Letter of Credit for another one year term.

Except to the extent inconsistent with the express provisions hereof, this
Letter of Credit is subject to and governed by Uniform Customs and Practice for
Documentary Credits (1993 Revision) International Chamber of Commerce
publication number 500.

                                           [Name of Bank]

                                           /s/ John McGuire
                                           ----------------------------
                                           Authorized Signature



                                                      INITIALS:

                                                      Landlord  ___________

                                                      Tenant    [ILLEGIBLE]
                                                                -----------

                               Exhibit E, Page 2