Document:

<Page>

                                                                   Exhibit 10.26

                            INDEMNIFICATION AGREEMENT

     THIS AGREEMENT is made and entered into this ___ day of _______________,
20__ by and between SYNTA PHARMACEUTICALS CORP., a Delaware corporation (the
"CORPORATION"), and _______________ ("AGENT").

                                    RECITALS

     WHEREAS, Agent performs a valuable service to the Corporation in his
capacity as [a director/an officer] of the Corporation;

     WHEREAS, the Corporation has adopted provisions in its Certificate of
Incoorporation (the "Charter") and bylaws (the "BYLAWS") providing for the
indemnification of the directors, officers, employees and other agents of the
Corporation, including persons serving at the request of the Corporation in such
capacities with other corporations or enterprises, as authorized by the Delaware
General Corporation Law, as amended (the "CODE");

     WHEREAS, the Charter, the Bylaws and the Code, by their non-exclusive
nature, permit contracts between the Corporation and its agents, officers,
employees and other agents with respect to indemnification of such persons; and

     WHEREAS, in order to induce Agent to serve as [a director/an officer] of
the Corporation, the Corporation has determined and agreed to enter into this
Agreement with Agent.

     NOW, THEREFORE, in consideration of Agent's service as [a director/an
officer] of the Corporation after the date hereof, the parties hereto agree as
follows:

                                    AGREEMENT

     1.   SERVICES TO THE CORPORATION. Agent will serve, at the will of the
Corporation or under separate contract, if any such contract exists, as [a
director/an officer] of the Corporation or as a director, officer or other
fiduciary of an affiliate of the Corporation (including any employee benefit
plan of the Corporation) faithfully and to the best of his ability so long as he
[is duly elected and qualified in accordance with the provisions of the Bylaws
or other applicable charter documents/is a duly appointed officer] of the
Corporation or such affiliate; PROVIDED, HOWEVER, that Agent may at any time and
for any reason resign from such position (subject to any contractual obligation
that Agent may have assumed apart from this Agreement) and that the Corporation
or any affiliate shall have no obligation under this Agreement to continue Agent
in any such position.

     2.   INDEMNITY OF AGENT. The Corporation hereby agrees to hold harmless and
indemnify Agent to the fullest extent authorized or permitted by the provisions
of the Charter, the Bylaws and the Code, as the same may be amended from time to
time (but, only to the extent that such amendment permits the Corporation to
provide broader indemnification rights than the Charter, the Bylaws or the Code
permitted prior to adoption of such amendment).

<Page>

     3.   ADDITIONAL INDEMNITY. In addition to and not in limitation of the
indemnification otherwise provided for herein, and subject only to the
exclusions set forth in Section 4 hereof, the Corporation hereby further agrees
to hold harmless and indemnify Agent:

          (a)  against any and all expenses (including attorneys' fees), witness
fees, damages, judgments, fines and amounts paid in settlement and any other
amounts that Agent becomes legally obligated to pay because of any claim or
claims made against or by him in connection with any threatened, pending or
completed action, suit or proceeding, whether civil, criminal, arbitrational,
administrative or investigative (including an action by or in the right of the
Corporation) to which Agent is, was or at any time becomes a party or a witness,
or is threatened to be made a party or a witness, by reason of the fact that
Agent is, was or at any time becomes a director, officer, employee or other
agent of Corporation, or is or was serving or at any time serves at the request
of the Corporation as a director, officer, employee or other agent of another
corporation, partnership, joint venture, trust, employee benefit plan or other
enterprise; and

          (b)  otherwise to the fullest extent as may be provided to Agent by
the Corporation under the non-exclusivity provisions of the Code, the Charter
and the Bylaws.

     4.   LIMITATIONS ON ADDITIONAL INDEMNITY. No indemnity pursuant to Section
3 hereof shall be paid by the Corporation:

          (a)  on account of any claim against Agent for an accounting of
profits made from the purchase or sale by Agent of securities of the Corporation
pursuant to the provisions of Section 16(b) of the Securities Exchange Act of
1934 and amendments thereto or similar provisions of any federal, state or local
statutory law;

          (b)  on account of Agent's conduct that is established by a final
judgment as knowingly fraudulent or deliberately dishonest or that constituted
willful misconduct;

          (c)  on account of Agent's conduct that is established by a final
judgment as constituting a breach of Agent's duty of loyalty to the Corporation
or resulting in any personal profit or advantage to which Agent was not legally
entitled;

          (d)  for which payment is actually made to Agent under a valid and
collectible insurance policy or under a valid and enforceable indemnity clause,
bylaw or agreement, except in respect of any excess beyond payment under such
insurance, clause, bylaw or agreement;

          (e)  if indemnification is not lawful (and, in this respect, both the
Corporation and Agent have been advised that the Securities and Exchange
Commission believes that indemnification for liabilities arising under the
federal securities laws is against public policy and is, therefore,
unenforceable and that claims for indemnification should be submitted to
appropriate courts for adjudication); or

          (f)  in connection with any proceeding (or part thereof) initiated by
Agent, or any proceeding by Agent against the Corporation or its directors,
officers, employees or other agents, unless (i) such indemnification is
expressly required to be made by law, (ii) the proceeding was authorized by the
Board of Directors of the Corporation, (iii) such

                                        2
<Page>

indemnification is provided by the Corporation, in its sole discretion, pursuant
to the powers vested in the Corporation under the Code, or (iv) the proceeding
is initiated pursuant to Section 9 hereof.

     5.   CONTINUATION OF INDEMNITY. All agreements and obligations of the
Corporation contained herein shall continue during the period Agent is a
director, officer, employee or other agent of the Corporation (or is or was
serving at the request of the Corporation as a director, officer, employee or
other agent of another corporation, partnership, joint venture, trust, employee
benefit plan or other enterprise) and shall continue thereafter so long as Agent
shall be subject to any possible claim or threatened, pending or completed
action, suit or proceeding, whether civil, criminal, arbitrational,
administrative or investigative, by reason of the fact that Agent was serving in
the capacity referred to herein.

     6.   PARTIAL INDEMNIFICATION. Agent shall be entitled under this Agreement
to indemnification by the Corporation for a portion of the expenses (including
attorneys' fees), witness fees, damages, judgments, fines and amounts paid in
settlement and any other amounts that Agent becomes legally obligated to pay in
connection with any action, suit or proceeding referred to in Section 3 hereof
even if not entitled hereunder to indemnification for the total amount thereof,
and the Corporation shall indemnify Agent for the portion thereof to which Agent
is entitled.

     7.   NOTIFICATION AND DEFENSE OF CLAIM. Not later than thirty (30) days
after Agent becomes aware, by written or other overt communication, of any
pending or threatened litigation, claim or assessment, Agent will, if a claim in
respect thereof is to be made against the Corporation under this Agreement,
notify the Corporation of such pending or threatened litigation, claim or
assessment; but the omission so to notify the Corporation will not relieve it
from any liability which it may have to Agent otherwise than under this
Agreement. With respect to any such pending or threatened litigation, claim or
assessment as to which Agent notifies the Corporation of the commencement
thereof:

          (a)  the Corporation will be entitled to participate therein at its
own expense;

          (b)  except as otherwise provided below, the Corporation may, at its
option and jointly with any other indemnifying party similarly notified and
electing to assume such defense, assume the defense thereof, with counsel
reasonably satisfactory to Agent. After notice from the Corporation to Agent of
its election to assume the defense thereof, the Corporation will not be liable
to Agent under this Agreement for any legal or other expenses subsequently
incurred by Agent in connection with the defense thereof except for reasonable
costs of investigation or otherwise as provided below. Agent shall have the
right to employ separate counsel in such action, suit or proceeding but the fees
and expenses of such counsel incurred after notice from the Corporation of its
assumption of the defense thereof shall be at the expense of Agent unless (i)
the employment of counsel by Agent has been authorized by the Corporation, (ii)
Agent shall have reasonably concluded, and so notified the Corporation, that
there is an actual conflict of interest between the Corporation and Agent in the
conduct of the defense of such action or (iii) the Corporation shall not in fact
have employed counsel to assume the defense of such action, in each of which
cases the fees and expenses of Agent's separate counsel shall be at the expense
of the Corporation. The Corporation shall not be entitled to assume the defense
of

                                        3
<Page>

any action, suit or proceeding brought by or on behalf of the Corporation or as
to which Agent shall have made the conclusion provided for in clause (ii) above;
and

          (c)  the Corporation shall not be liable to indemnify Agent under this
Agreement for any amounts paid in settlement of any action or claim effected
without its written consent, which shall not be unreasonably withheld. The
Corporation shall be permitted to settle any action or claim except that it
shall not settle any action or claim in any manner which would impose any
penalty or limitation on Agent without Agent's written consent, which may be
given or withheld in Agent's sole discretion.

     8.   EXPENSES. The Corporation shall advance, prior to the final
disposition of any proceeding, promptly following request therefor, all expenses
incurred by Agent in connection with such proceeding upon receipt of an
undertaking by or on behalf of Agent to repay said amounts if it shall be
determined ultimately that Agent is not entitled to be indemnified under the
provisions of this Agreement, the Charter, the Bylaws, the Code or otherwise.

     9.   ENFORCEMENT. Any right to indemnification or advances granted by this
Agreement to Agent shall be enforceable by or on behalf of Agent in any court of
competent jurisdiction if (i) the claim for indemnification or advances is
denied, in whole or in part, or (ii) no disposition of such claim is made within
ninety (90) days of request therefor. Agent, in such enforcement action, if
successful in whole or in part, shall be entitled to be paid also the expense of
prosecuting his claim. It shall be a defense to any action for which a claim for
indemnification is made under Section 3 hereof (other than an action brought to
enforce a claim for expenses pursuant to Section 8 hereof, PROVIDED that the
required undertaking has been tendered to the Corporation) that Agent is not
entitled to indemnification because of the limitations set forth in Section 4
hereof. Neither the failure of the Corporation (including its Board of Directors
or its stockholders) to have made a determination prior to the commencement of
such enforcement action that indemnification of Agent is proper in the
circumstances, nor an actual determination by the Corporation (including its
Board of Directors or its stockholders) that such indemnification is improper
shall be a defense to the action or create a presumption that Agent is not
entitled to indemnification under this Agreement or otherwise.

     10.  SUBROGATION. In the event of payment under this Agreement, the
Corporation shall be subrogated to the extent of such payment to all of the
rights of recovery of Agent, who shall execute all documents required and shall
do all acts that may be necessary to secure such rights and to enable the
Corporation effectively to bring suit to enforce such rights.

     11.  NON-EXCLUSIVITY OF RIGHTS. The rights conferred on Agent by this
Agreement shall not be exclusive of any other right which Agent may have or
hereafter acquire under any statute, provision of the Corporation's Certificate
of Incorporation or Bylaws, agreement, vote of stockholders or directors, or
otherwise, both as to action in his official capacity and as to action in
another capacity while holding office.

     12.  SURVIVAL OF RIGHTS.

          (a)  The rights conferred on Agent by this Agreement shall continue
after Agent has ceased to be a director, officer, employee or other agent of the
Corporation or to serve

                                        4
<Page>

at the request of the Corporation as a director, officer, employee or other
agent of another corporation, partnership, joint venture, trust, employee
benefit plan or other enterprise, and shall inure to the benefit of Agent's
heirs, executors and administrators.

          (b)  The Corporation shall require any successor (whether direct or
indirect, by purchase, merger, consolidation or otherwise) to all or
substantially all of the business or assets of the Corporation, expressly to
assume and agree to perform this Agreement in the same manner and to the same
extent that the Corporation would be required to perform if no such succession
had taken place.

     13.  SEPARABILITY. Each of the provisions of this Agreement is a separate
and distinct agreement and independent of the others, so that if any provision
hereof shall be held to be invalid or unenforceable for any reason, such
invalidity or unenforceability shall not affect the validity or enforceability
of the other provisions hereof. Furthermore, if this Agreement shall be
invalidated in its entirety on any ground, then the Corporation shall
nevertheless indemnify Agent to the fullest extent provided by the Charter, the
Bylaws, the Code or any other applicable law.

     14.  GOVERNING LAW. This Agreement shall be interpreted and enforced in
accordance with the laws of the State of Delaware.

     15.  AMENDMENT AND TERMINATION. No amendment, modification, termination or
cancellation of this Agreement shall be effective unless in writing signed by
both parties hereto.

     16.  IDENTICAL COUNTERPARTS. This Agreement may be executed in one or more
counterparts, each of which shall for all purposes be deemed to be an original
but all of which together shall constitute but one and the same Agreement. Only
one such counterpart need be produced to evidence the existence of this
Agreement.

     17.  HEADINGS. The headings of the sections of this Agreement are inserted
for convenience only and shall not be deemed to constitute part of this
Agreement or to affect the construction hereof.

     18.  NOTICES. All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given (i)
upon delivery if delivered by hand to the party to whom such communication was
directed or (ii) upon the third business day after the date on which such
communication was mailed if mailed by certified or registered mail with postage
prepaid:

          (a)  If to Agent, at the address indicated on the signature page
hereof.

          (b)  If to the Corporation, to:

               Synta Pharmaceuticals Corp.
               45 Hartwell Avenue
               Lexington, MA 02421
               Attention: Chief Executive Officer

                                        5
<Page>

     or to such other address as may have been furnished to Agent by the
Corporation.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement on and
as of the day and year first above written.

                                          SYNTA PHARMACEUTICALS CORP.

                                          By:
                                             --------------------------
                                          Name:
                                          Title:

                                          AGENT

                                          -----------------------------
                                          [Name]

                                          Address:

                                          -----------------------------
                                          -----------------------------

                                        6QuickLinks
 -- Click here to rapidly navigate through this document
  

 
 

EXHIBIT 10.5    
    

        CONFIDENTIAL PORTIONS HAVE BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT AND HAVE BEEN FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION (THE "COMMISSION").

AMERICAN DG ENERGY INC.  

FACILITIES, SUPPORT SERVICES AND BUSINESS AGREEMENT

January 1, 2006  

        THIS FACILITIES AND SUPPORT SERVICES AGREEMENT is effective as of January 1, 2006 between
Tecogen Inc., a Delaware corporation ("Tecogen"), and American DG Energy Inc., a Delaware corporation ("ADG
Energy"). 

        NOW,
THEREFORE, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereby agree as follows: 

 1.    Office and Infrastructure

        Tecogen
will provide to ADG Energy the following office and infrastructure support services for a period from the date of this Agreement through the Termination Date (as such term is
defined in Section 2 below): 

        (a)    Office Space.    Approximately 540 allocated square feet of space in Tecogen's offices located at 45 First
Avenue, Waltham, Massachusetts 02451 (the "Building"), which shall include three (3) offices and a shared conference room. Tecogen will also
provide ADG Energy with water, sewer, electrical, phones and other utility services, heating, ventilation and air-conditioning, and cleaning and janitorial services. Tecogen may change the
space in the Building occupied by ADG Energy from time to time during the term of this Agreement. Tecogen will provide such space and services at a flat rate of $716.00 per month. If additional space
is provided, this flat fee will increase at an annual rate of $15.91 per square foot for the additional space. Copy machine usage, office supplies, postage and shipping, secretarial &
receptionist services, Internet service, telephone support and IT support are not included in the monthly rate and will be billed separately. 

        (b)    Personnel Support.    Tecogen or ADG Energy will provide services to each other, on an as-available
basis, accounting, tax, treasury and financial services, information systems services, human resource services, secretarial and such other services and support as Tecogen or ADG Energy may request.
Tecogen or ADG Energy will be allocated the cost of such services at a rate equal to the individual's base salary times 2.3 for each employee or consultant assigned, but Tecogen or ADG Energy will
only be required to pay for such personnel while they are working on Tecogen or ADG Energy's behalf. ADG Energy shall record the time spent by such personnel on a spreadsheet and Tecogen shall record
the time spent on a time-card system but in either case the hours spent should get pre-approved by management before any work starts. 

        (c)    Insurance and Employee Benefit Plans.    To the extent it is able to do under its then current plans and
policies, Tecogen will include ADG Energy as a covered entity under its liability, property and casualty, directors' and officers' insurance, workers compensation and other applicable business
insurance policies. Tecogen will allow ADG Energy employees to participate in Tecogen's medical and dental insurance plans, 401K savings plan and other group insurance plans for its employees,
including life, AD&D, and short and long-term disability plans. The costs of these insurance programs will be charged to ADG Energy on an actual cost basis when available, or in the case
of general insurance be allocated to ADG Energy for it's pro rata share of the premiums. Management of the plans will be carried out jointly by both companies and with no charge to each other. 

1

 

        (d)    Product Pricing for Turnkeys and ADG Energy Projects:    Tecogen agrees to sell products (cogen and chillers)
at its best dealer pricing, [**THE CONFIDENTIAL PORTION HAS BEEN SO OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT AND HAS BEEN FILED SEPARATELY WITH THE
COMMISSION.**] times list price. For the purposes of this calculation, Tecogen's current SELECT© pricing software revision shall be used for standard
models and listed options. Special options shall be negotiated on a case-by-case basis. 

        (e)    Spares Pricing:    Spare parts shall be sold at our best contractor/dealer discount,
[**THE CONFIDENTIAL PORTION HAS BEEN SO OMITTED PURSUANT TO A
REQUEST FOR CONFIDENTIAL TREATMENT AND HAS BEEN FILED SEPARATELY WITH THE COMMISSION.**] times list price. 

        (f)    Volume Discounts:    Upon achieving $1M in total sales for a single year (combined parts and units) all parts
and modules thereafter shall be supplied at a further 10% discount, i.e., [**THE CONFIDENTIAL PORTION HAS BEEN SO OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT AND HAS BEEN FILED SEPARATELY WITH THE COMMISSION.**] times list for modules and [**THE CONFIDENTIAL PORTION HAS BEEN
SO OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT AND HAS BEEN FILED SEPARATELY WITH THE COMMISSION.**] for spares. Total sales dollars shall be the
combined total of ADG Energy and ADG Energy LLC. Purchases made by AES NJ shall not be credited to the total, however. 

        (g)    Exclusivity:    ADG Energy shall be granted exclusive representation rights to the Tecogen Cogeneration Product
in the New England States, and Tecogen shall be granted exclusive right to service all ADG Energy equipment in the New England region. Tecogen shall be granted exclusive representation rights to the
ADG Energy Cogeneration Product in California. The relevant portions of Tecogen's standard rep agreement shall apply except where in conflict with this agreement. ADG Energy will be eligible for split
commissions for cogeneration and chiller products as presented in Tecogen's standard rep agreement. 

        (h)    Sourcing of Spares:    Except in exceptional circumstances (such as ADG Energy LLC), ADG Energy agrees
to procure all parts for Tecogen modules from Tecogen. 

        (i)    Service:    Service for all ADG Energy units contracted to Tecogen will be at the rate of
[**THE CONFIDENTIAL PORTION HAS BEEN SO OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT AND HAS BEEN FILED SEPARATELY WITH THE COMMISSION.**]
/run hour for a 75 kW and [**THE CONFIDENTIAL PORTION HAS BEEN SO OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT AND HAS BEEN
FILED SEPARATELY WITH THE COMMISSION.**] /run hour for a 60 kW (new units without emissions control). Emissions control units will be contracted at a $0.15/run hour
premium. Used units shall be priced at the same rate after rehabilitation costs are settled. Tecogen shall only bill ADG Energy for the actual hours and services rendered during each month without any
pre-billing. 

        (j)    Service Commission:    ADG Energy shall receive a 5% commission for all new service sales it sells to end
customers based on the prices presented in (i) above (par). ADG Energy and Tecogen will share 50/50 on profit for amounts above par. The commission percent will be lowered
accordingly for all sales prices below par. Tecogen shall approve all end customer service agreements. 

        (k)    Billable Service:    Billable service provided by Tecogen shall be billed at the standard rate of $95/hr less
$20/hr discount. Overtime service shall be billed at $100/hr and covers hours worked where Tecogen is obligated to pay its employees at the overtime rate. Parts shall be billed at the pricing levels
established above. 

2

 

        (l)    Non-exclusive Territories:    For other territories and products ADG Energy shall have
non-exclusive rep status. 

        (m)    Payments.    All payments shall be paid no later than thirty (30) days following the date of invoice.

 2.    Term

        The
term of this agreement commenced as of the effective date for one year, renewable annually upon mutual written agreement. 

 3.    Representations and warranties of ADG

        Tecogen
represents and warrants to ADG Energy as follows, in each case as of the Effective Date: 

        (a)    Organization and Corporate Power.    Tecogen is a corporation duly organized, validly existing and in good
standing under the laws of Delaware, and is duly qualified or registered to do business and is in good standing as a foreign corporation in each jurisdiction in which the failure to be so qualified
would have a material adverse effect on Tecogen. Tecogen has all required corporate power and authority to carry on its business as presently conducted, to enter into and perform this Agreement and to
carry out the transactions contemplated by this Agreement. 

        (b)    Authority and Non-Contravention.    Tecogen has full right, authority and power under its
Certificate of Incorporation and By-Laws to enter into this Agreement and to carry out the transactions contemplated by this Agreement, and the execution, delivery and performance by
Tecogen of this Agreement have been duly authorized by all necessary action under Tecogen's Certificate of Incorporation and By-Laws. This Agreement constitutes the valid and binding
obligation of Tecogen enforceable in accordance with its terms, except (a) as limited by applicable bankruptcy, insolvency, reorganization, moratorium, and other laws of general application
affecting enforcement of creditors' rights generally or by equitable principles, (b) as limited by laws relating to the availability of specific performance, injunctive relief, or other
equitable remedies and (c) to the extent that the enforceability of the indemnification provisions in this Agreement may be limited by applicable law. 

 4.    Representations and Warranties of ADG Energy

        In
order to induce Tecogen to enter into this Agreement and to consummate the transactions contemplated by this Agreement, ADG Energy makes to Tecogen the representations and warranties
contained in this Section 4, in each case as of the date of this Agreement. 

        (a)    Organization and Corporate Power.    ADG Energy is a corporation duly organized, validly existing and in good
standing under the laws of Delaware. ADG Energy has all required corporate power and authority to carry on its business as presently conducted, to enter into and perform this Agreement and to carry
out the transactions contemplated by this Agreement. 

        (b)    Authority and Non-Contravention.    ADG Energy has full right, authority and power under its
Certificate of Incorporation and By-Laws to enter into this Agreement and to carry out the transactions contemplated by this Agreement, and the execution, delivery and performance by ADG
Energy of this Agreement have been duly authorized by all necessary action under ADG Energy's Certificate of Incorporation and By-Laws. This Agreement constitutes the valid and binding
obligation of ADG Energy enforceable in accordance with its terms, except (a) as limited by applicable bankruptcy, insolvency, reorganization, moratorium, and other laws of general application
affecting enforcement of creditors' rights generally or by equitable principles, (b) as limited by laws relating to the availability of specific performance, injunctive relief, or other
equitable remedies and (c) to the 

3

 

extent
that the enforceability of the indemnification provisions in this Agreement may be limited by applicable law. 

 5.    General

        (a)    Independent Entities.    Nothing in this Agreement shall be construed to constitute Tecogen and ADG Energy as a
partner, franchisee, or agent of one another, nor shall either party have any authority to bind the other in any respect. Neither party has the power to make contracts in the name of the other, or to
incur any liabilities whatsoever in the name of the other. Each party shall remain an independent contractor responsible only for its own actions. 

        (b)    Confidentiality.    Unless otherwise expressly provided for in this Agreement, both parties shall treat any
information provided by or obtained from the other as proprietary or confidential and shall not disclose any such confidential information to any third party during the term of this Agreement or for a
period of five (5) years thereafter, except for information which (i) at the time of disclosure, was published, known publicly or otherwise in the public domain; (ii) after
disclosure, is published, becomes known publicly or otherwise becomes part of the public domain through no fault of the receiving party; (iii) prior to the time of disclosure, is known to the
receiving party as evidenced by its written records and is not then subject to an obligation of confidentiality to any third party; and (iv) after disclosure, is made available to the receiving
party in good faith by a third party under no obligation of confidentiality and without restriction on its further disclosure by the receiving party. Notwithstanding the preceding sentence, either
party may disclose confidential information of the other and this Agreement to their legal representatives and employees and advisers to the extent such disclosure is reasonably necessary to achieve
the purposes of this Agreement; or in connection with the filing and support of patent applications; or as required by law or to comply with applicable governmental regulations or court order;
provided that if a party is required to make such disclosure of the other party's confidential information, other than pursuant to a confidentiality agreement, it will give reasonable advance notice
to the other party of such disclosure and, save to the extent inappropriate in the case of patent applications, will use its reasonable best efforts to secure confidential treatment of such
information in consultation with the other party prior to its disclosure and disclose only the minimum necessary to comply with such requirements. 

        (c)    Amendments, Waivers and Consents.    No provision of this Agreement may be waived otherwise than by a written
instrument signed by the party or parties so waiving such covenant or other provision. No amendment to this Agreement may be made without the written consent of ADG Energy and Tecogen. 

        (d)    Governing Law.    This Agreement shall be deemed to be a contract made under, and shall be construed in
accordance with, the laws of the Commonwealth of Massachusetts, without giving effect to conflict of laws principles thereof. 

        (e)    Counterparts.    This Agreement may be executed in multiple counterparts, each of which shall constitute one
and the same instrument. One or more counterparts of this Agreement may be delivered via telecopy, with the intention that they shall have the same effect as an original counterpart hereof. 

        (f)    Notices and Demands.    Any notice or demand which is required or provided to be given under this Agreement
shall be deemed to have been sufficiently given and received for all purposes when delivered by hand, telecopy, telex or other method of facsimile, or five (5) business days after being sent by
certified or registered mail, postage and charges prepaid, return receipt requested, or two (2) business days after being sent by overnight delivery providing receipt of delivery: 

        if
to Tecogen Inc., 45 First Avenue, Waltham, Massachusetts 02451, Attention: President. 

4

 

        if
to AmericanDG Energy Inc., 45 First Avenue, Waltham, Massachusetts 02451, Attention: President. 

        (g)    Dispute Resolution    

        (i)    All
disputes, claims, or controversies arising out of or relating to this Agreement or the negotiation, validity or performance of this Agreement or the transactions
contemplated by this Agreement that are not resolved by mutual agreement shall be resolved solely and exclusively by binding arbitration to be conducted before the American Arbitration Association
("AAA"). If AAA ceases operations, then the parties shall select a comparable organization that provides qualified arbitration services. The arbitration shall be held in Boston, Massachusetts before a
single arbitrator and shall be conducted in accordance with the rules and regulations promulgated by AAA unless specifically modified herein. 

        The
parties covenant and agree that the arbitration hearing shall commence within ninety (90) days of the date on which a written demand for arbitration is filed by any party
hereto. In connection with the arbitration proceeding, the arbitrator shall have the power to order the production of documents by each party and any third-party witnesses. In addition, each party may
take up to three depositions as of right, and the arbitrator may in his or her discretion allow additional depositions upon good cause shown by the moving party. However, the arbitrator shall not have
the power to order the answering of interrogatories or the response to requests for admission. In connection with any arbitration, each party shall provide to the other, no later than seven
(7) business days before the date of the arbitration hearing, the identity of all persons that may testify at the arbitration and a copy of all documents that may be introduced at the
arbitration hearing or considered or used by a party's witness or expert. The arbitrator's decision and award shall be made and delivered within three (3) months of the selection of the
arbitrator. The arbitrator's decision shall set forth a reasoned basis for any finding of liability or award of damages. The arbitrator shall not have power to award damages in excess of actual
compensatory damages and shall not multiply actual damages or award punitive damages or any other damages that are specifically excluded under this Agreement, and each party hereby irrevocably waives
any claim to such damages. 

        The
parties covenant and agree that they will participate in the arbitration in good faith and that they will share equally its costs, except as otherwise provided herein. The arbitrator
may in his or her discretion assess costs and expenses (including the reasonable legal fees and expenses of the prevailing party whether claimant or respondent) against any party to a proceeding. Any
party failing or refusing to comply with a valid order of the arbitrators issued in accordance with this Section 5(g)(i) shall be liable for costs and expenses, including attorneys'
fees, incurred by the other party in enforcing the order. Nothing in this Section 5(g)(i) shall prohibit any party from proceeding in court without prior arbitration for the limited
purpose of seeking a temporary or permanent injunction to avoid immediate and irreparable harm. The provisions of this Section 5(g)(i) shall be enforceable in any court of competent
jurisdiction. 

        Unless
otherwise ordered, the parties shall bear their own attorneys' fees, costs and expenses in connection with the arbitration. The parties will share equally in the fees and expenses
charged by AAA. 

        (ii)   Each
of the parties hereto irrevocably and unconditionally consents to the exclusive use of AAA to resolve all disputes, claims or controversies arising out of or
relating to this Agreement or any other agreement executed and delivered pursuant to this Agreement or the negotiation, validity or performance hereof and thereof or the transactions contemplated
hereby and thereby and further consents to the jurisdiction of the courts of the Commonwealth of Massachusetts for the purposes of enforcing the arbitration provisions of
Section 5(g)(i) of this Agreement. Each party further irrevocably waives any objection to proceeding before AAA based upon lack of personal jurisdiction or to the laying of venue and
further irrevocably and unconditionally waives and agrees not to make a claim in 

5

 

any
court that arbitration before AAA has been brought in an inconvenient forum. Each of the parties hereto hereby consents to service of process by registered mail at the address to which notices are
to be given. Each of the parties hereto agrees that its or his submission to jurisdiction and its or his consent to service of process by mail is made for the express benefit of the other parties
hereto. 

        (h)    Assignment.    The rights and obligations of the parties under this Agreement may not be assigned or
transferred in any manner without the prior express written approval of the other party. 

        IN
WITNESS WHEREOF, the parties hereto have caused this Facilities and Support Services Agreement to be duly executed and delivered by their proper and duly authorized representatives as
of the day and year first above written. 

Dated:
January 6, 2006 

	TECOGEN INC.	 	AMERICAN DG ENERGY INC.
	

By:	

	
 	

By:	

	Name:  Robert A. Panora	 	Name:  Barry J. Sanders
	Title:    President	 	Title:    President

6

QuickLinks

EXHIBIT 10.5

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00113-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00113-of-00352.parquet"}]]