Exhibit
10.12

    SUBSCRIPTION
AGREEMENT

    


    Gentlemen:

    


    1.           Subscription.  The
undersigned, intending to be legally bound, irrevocably subscribes for and
agrees to purchase the aggregate number of Shares of the Company’s common stock
(“Common Stock”), par value $.01 per share, of American DG Inc., a Delaware
corporation (the “Company”), at a purchase price of $1.00 per Share (the
“Purchase Price”) indicated on the signature page hereof, on the terms and
conditions described herein and in the Confidential Private Placement Memorandum
dated June 27, 2002 (which, together with all exhibits, attachments, amendments
and supplements thereto, is referred to as the “Memorandum”).  The
undersigned herewith delivers to the Company the consideration (“Purchase
Price”) required to purchase the Shares subscribed for hereunder by wire
transfer funds payable to American DG Inc., 85 First Avenue, Waltham, MA 02451
in the amount of $1.00 for each Share subscribed for hereunder. The minimum
investment is for $50,000 (50,000 Shares) unless otherwise determined in the
discretion of the Company. The Shares will be issued in accordance with the
terms and conditions set forth in the Memorandum. Capitalized terms not
otherwise defined in this Agreement have the meanings specified in the
Memorandum.

    


    2.           Investor Representations,
Warranties and Covenants. The undersigned hereby acknowledges, represents
and warrants to, and agrees with the Company as follows:

    


    a.      The
undersigned is acquiring the Shares for the undersigned’s own account as
principal, for investment purposes only, and not with a view to, or for, resale
or distribution of all or any part of the Shares, and no other person has a
direct or indirect beneficial interest in such Shares;

    


    b.      The
undersigned acknowledges its understanding that the offering and sale of the
Shares is intended to be exempt from registration under the Securities Act of
1933, as amended (the “Securities Act”), by virtue of Section 4(2) of the
Securities Act and Rule 506 of Regulation D (“Regulation D”) promulgated
thereunder and Section 4(6) of the Securities Act, and, in furtherance thereof,
the undersigned represents and warrants to and agrees with the Company that the
undersigned has the financial ability to bear the economic risk of the
undersigned’s investment, has adequate means for providing for the undersigned’s
current needs and contingencies and has no need for liquidity with respect to
the undersigned’s investment in the Shares.

    


    c.      The
undersigned is an “accredited investor” as defined in Rule 501(a) of Regulation
D under the Securities Act and has completed the Accredited Investor
Questionnaire furnished herewith;

    


    
      d.     The
undersigned:

    

    


    i.     has
been furnished with a copy of the Memorandum and any other documents which have
been made available upon request and the undersigned has carefully read the
Memorandum and understands and has evaluated the risks of a purchase of Shares,
including the risks set forth under “Risk Factors” in the Memorandum; and has
relied solely on the information contained in the Memorandum, and any
supplemental written information furnished pursuant to Subsection (ii)
below;

    


    ii.     has
been given the opportunity to ask questions of and receive answers from the
Company concerning the terms and conditions of the Offering of the Shares, and
has been given the opportunity to obtain additional information necessary to
satisfy himself as to the accuracy of the information contained in the
Memorandum to the extent that the Company possesses such information or can
acquire it without unreasonable effort or expense and has not been furnished
with any other offering literature except as referred to in the
Memorandum;

    


    iii.     has
not relied on any oral representation, warranty or information in connection
with the Offering of the Shares by the Company, or any officer, employee, agent
or affiliate of the Company or the Placement Agent;

    


    iv.     has
determined the Shares are a suitable investment for the undersigned and that at
this time the undersigned can bear a complete loss of the undersigned’s
investment therein;

    


    v.     has
such knowledge and experience in financial and business matters that the
undersigned is capable of evaluating the merits and risks of the undersigned’s
investment in the Shares;


    
      
         


      

      
        1

        
          

        

      

      
         


      

    

    


    vi.     If
the undersigned is a corporation, limited liability company, partnership, trust,
qualified plan or other entity, it is authorized and qualified to become a
holder of Shares, and the person signing this Subscription Agreement on behalf
of such entity has been duly authorized to do so;

    


    vii.    Any
information which the undersigned has heretofore furnished and herewith
furnishes to the Company with respect to the undersigned’s financial position
and business experience, including, without limitation, the undersigned’s
Accredited Investor Questionnaire, is correct and complete as of the date of
this Agreement and if there should be any material change in such information
prior to issuance to the undersigned of Shares, the Undersigned will immediately
furnish such revised or corrected information to the Company;

    


    viii.   The
foregoing acknowledgments, representations, warranties and agreements shall
survive the closing at which the Shares are issued;

    


    ix.     The
undersigned acknowledges that the undersigned has not purchased the Shares as a
result of any general solicitation or general advertising; and

    


    x.     
The undersigned’s overall commitment to investments which are not readily
marketable is not disproportionate to the undersigned’s net worth, and the
undersigned’s prospective investment in the Company and will not cause such
overall commitment to become excessive.

    


    3.           Investor
Awareness.  The undersigned acknowledges that:

    


    a.      No
federal or state agency has passed upon the Shares or made any finding or
determination as to the fairness of this investment;

    


    b.      There
is no established market for the Shares and no assurance has been given that any
public market for them will develop;

    


    c.      The
Shares may not be sold, pledged or otherwise transferred, except as may be
permitted under the Securities Act and applicable state securities laws pursuant
to registration or exemption therefrom; and accordingly, the undersigned may be
required to bear the financial risks of an investment in the Shares for an
indefinite period of time;

    


    d.      The
undersigned consents to (i) the placing of a legend substantially in the form
set forth below on the certificates representing the Shares stating that the
securities have not been registered and setting forth the restriction on
transfer contemplated hereby, and (ii) the placing of a stop transfer order on
the books of the Company and with any transfer agents against the securities
included within the Shares.

    


    A legend
shall be placed on certificates representing the Shares substantially in the
form set forth below:

    


    “THE
SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS, AND MAY
NOT BE TRANSFERRED, SOLD OR OTHERWISE DISPOSED OF WITHOUT AN EFFECTIVE
REGISTRATION STATEMENT UNDER SUCH ACT OR PURSUANT TO AN EXEMPTION FROM THE
REGISTRATION REQUIREMENTS OF SUCH ACT AND APPLICABLE STATE SECURITIES LAWS,
SUPPORTED BY AN OPINION OF COUNSEL, REASONABLY SATISFACTORY TO THE COMPANY AND
ITS COUNSEL, THAT SUCH REGISTRATION IS NOT REQUIRED.”

    


    4.           Miscellaneous.

    


    a.      Indemnity. The
undersigned agrees to indemnify and hold harmless the Company and its
affiliates, the Placement Agent and its affiliates, and each of their respective
directors, officers, employees, agents and controlling persons (the Company, the
Placement Agent, and each such person being an “Indemnified Party”), from and
against any and all losses, claims, damages, liabilities and expenses whatsoever
(including, but not limited to, any and all expenses whatsoever reasonably
incurred investigating, preparing or defending against any litigation commenced
or threatened or any claim whatsoever), joint or several, as incurred, to which
such Indemnified Party may become subject under any applicable United States
federal or state law or the laws of any other domestic or foreign jurisdiction,
or otherwise, and related to or arising out of or based upon any false
representation, warranty or acknowledgment, or breach or failure by the
undersigned to comply with any covenant or agreement made by the undersigned
herein or in any other document furnished by the undersigned to any of the
foregoing in connection with this transaction.


    
      
         


      

      
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    b.      Modification.  Except
as otherwise provided herein, neither this Agreement nor any provisions hereof
shall be modified, discharged or terminated except by an instrument in writing
signed by the party against whom any waiver, change, discharge or termination is
sought.

    


    c.      Binding
Effect.  Except as otherwise provided herein, this Agreement
shall be binding upon and inure to the benefit of the parties and their heirs,
executors, administrators, successors, legal representatives and
assigns.  If the undersigned is more than one person, the obligation
of the undersigned shall be joint and several and the agreements,
covenants,  representations, warranties and acknowledgments herein
contained shall be deemed to be made by and be binding upon each such person and
his heirs, executors, administrators and successors.

    


    d.      Entire
Agreement.  This instrument contains the entire agreement of
the parties and there are no representations, warranties, acknowledgments,
covenants or other agreements except as stated or referred to
herein.

    


    e.      Assignability.  This
Agreement is not transferable or assignable by the undersigned.

    


    f.      Law
Governing.  This Agreement shall be enforced, governed and
construed in all respects in accordance with the laws of the State of
Massachusetts, without giving effect to conflicts of laws
principles.


    
      
         


      

      
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    ALL SUBSCRIBERS MUST
COMPLETE THIS PAGE


    


    IN
WITNESS WHEREOF, the undersigned has executed this Agreement on the day of
                                  ,
2002.

    


    $  _________________

       Total
Purchase Price

    


    Please
note that the number of Shares you receive will be based upon the total purchase
price.

    


    Manner in
which Title is to be held (Please Check One):

    


    
      1.  _____  Individual

       

      
      

    

    
      2.  _____  Joint
Tenants with Right of Survivorship

    

    


    
      3.  _____  Community
Property

    

    


    
      4.  _____  Tenants
in Common

    

    


    
      5.  _____  Corporation
/ Limited Liability Company / Partnership

    

    


    
      6.  _____  IRA

    

    


    
      7.  _____  Trust
/ Estate / Pension or Profit Sharing Plan Date
Opened: __________

    

    


    
      8.  _____  As
a Custodian for __________________ Under the Uniform Gift to Minors
Act   of the State of __________________

      
      

    

    
       

      9.  _____  Married
with Separate Property

    

    


    
      10.  _____  Keogh

    

    


    
      11.  _____  Tenants
by the Entirety

    


    
      
         


      

      
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    EXECUTION BY NATURAL
PERSONS

    
  

    
      
        

      

    

    Exact
Name in Which Title is to be Held

    


    
      
        
          
            
              
                
                  
                    
                      
                        
                          
                            
                              
                                	
                                         

                                      	 
      	
                                         

                                      
	
                                        Name
      of Purchaser (Print)

                                      	 
      	
                                        Name
      of Additional Purchaser

                                      
	 
      	 
      	 
      
	
                                         

                                      	 
      	
                                         

                                      
	
                                        Address

                                      	 
      	
                                        Address

                                      
	 
      	 
      	 
      
	
                                         

                                      	 
      	
                                         

                                      
	
                                        City,
      State and Zip Code

                                      	 
      	
                                        City,
      State and Zip Code

                                      
	 
      	 
      	 
      
	
                                         

                                      	 
      	
                                         

                                      
	
                                        Social
      Security Number

                                      	 
      	
                                        Social
      Security Number

                                      
	 
      	 
      	 
      
	
                                         

                                      	 
      	
                                         

                                      
	
                                        Signature
      of Purchaser

                                      	 
      	
                                        Signature
      of Additional
Purchaser

                                      


                              

                            

                          

                        

                      

                    

                  

                

              

            

          

        

      

    

     

    ACCEPTED
this         day of ___________,
2002 on behalf of the Company.


    


    
      
        
          
            	 
      	
                    By:

                  	 
      	 
      
	 
      	 
      	 
      	 
      
	 
      	
                    Name:

                  	 
      	 
      
	 
      	 
      	 
      	 
      
	 
      	
                    Title:

                  	 
      	 
      


          

        

      

    

     

    
      
         


      

      
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    EXECUTION BY SUBSCRIBER THAT
IS AN ENTITY


    


    (Corporation,
Limited Liability Company, Partnership, Trust, Etc.)


     

     

    
      
        

      

    

    Name of
Entity (Please Print)

    


    
      
        	
                Date of Incorporation or Organization:

              	 
      


      

    

    


    
      
        	
                State of Principal Offices:

              	 
      


      

    

    


    
      
        	
                Federal Taxpayer Identification Number:

              	 
      


      

    

    


    
      
        
          
            	 
      	
                    By:

                  	 
      
	 
      	 
      	 
      
	 
      	
                    Title:

                  	 
      


          

        

      

    

    


    
      
        
          
            
              
                
                  
                    
                      	Attest:	
                               

                            	 
      	 
      
	
                              (If
      Entity is a Corporation)

                            	 
      	 
      
	 
      	 
      	 
      
	 
      	 
      	
                              Address

                            
	 	 	 
	 
      	 
      	 
      
	 
      	 
      	
                              Taxpayer
      Identification
Number

                            


                    

                  

                

              

            

          

        

      

    

    


    ACCEPTED this             
 day of ___________, 2002 on behalf of the Company.

    


    
      
        
          
            
              
                	 
      	 
      	
                        By:

                      	 
      
	 
      	 
      	 
      	 
      
	 
      	 
      	
                        Name:

                      	 
      
	 
      	 
      	 
      	 
      
	 
      	 
      	
                        Title:

                      	 
      


              

            

          

        

      

    

     

    
      
         


      

      
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