SecProbe.io

May24, 2012
 Via E-mail

John N. Hatsopoulos Chief Executive Officer Tecogen Inc. 45 First Avenue Waltham, MA 02451
Re: Tecogen Inc.
Amendment No. 1 to Registrati on Statement on Form S-1
Filed April 27, 2012
  File No. 333-178697

Dear Mr. Hatsopoulos:

We have reviewed your response letter a nd the above-referenced filing, and have the
following comments.    Amendment No. 1 to Registration Statement on Form S-1

 General

1. Please revise your document to include updated financial statements in accordance with
Rule 8-08 of Regulation S-X.
2. Since you appear to qualify as an “emerging growth company,” as defined in the
Jumpstart Our Business Startups Act (“the Act”), please disclose  on your prospectus
cover page that you are an emerging growth  company, and revise your prospectus to
provide the following additional disclosures:
 Describe how and when a company may lose emerging growth company status;

 A brief description of the various exemptions that ar e available to you, such as
exemptions from Section 404(b) of the Sarbanes-Oxley Act of 2002 and Section
14A(a) and (b) of the Securities Exchange Act of 1934; and
 Your election under Secti on 107(b) of the Act:

o If you have elected to opt out
 of the extended transition period for
complying with new or revised accoun ting standards pursuant to Section
107(b) of the Act, include a statement that the election is  irrevocable; or

John N. Hatsopoulos Tecogen Inc. May24, 2012 Page 2

 If you have elected to use the extend ed transition period for complying
with new or revised accounting stan dards under Section 102(b)(2)(B) of
the Act, provide a risk factor explai ning that this election allows you to
delay the adoption of new or revi sed accounting standards that have
different effective dates for public  and private companies until those
standards apply to private companies.  Please state in your risk factor that,
as a result of this election, your financial statements may not be comparable to companies that comply with public company effective dates.  Include a similar statemen t in your critical accounting policy
disclosures in MD&A.
 Risk Factors, page 6

3. We note your response to comment 11 of our letter dated January 18, 2012.  However,
we continue to believe that to the extent th at there are certain risks facing your company
that are similar to early-stage companies, please tailor such risks so that they apply
specifically to the circumstances of your comp any.  For example, your risk stating that
businesses and consumers might not adopt  cogeneration should discuss whether
businesses have adopted such technology in the last several decades th at you have offered
such technology.  Further, to the extent the risks relate to newly introduced technology,
such as your new Ultra-low emissions technol ogy, the risk factors should clearly state
this fact.  Please note that these are just examples.  Please comprehensively revise your risk factors to ensure that each of them reflects the current state of your business and
explains the specific risk as applied to th e specific facts and circumstances of your
company.  For additional guidance, pleas e see Staff Legal Bulletin No. 7 (1999).

4. We note your response to comment 12 of our letter dated January 18, 2012.  However, it
does not appear that you have revi sed your risk factors so that they cite specific examples
of how the risks have imp acted your business so that investors may have a better
understanding of how these risks could impact your future results and financial condition.
As one example, we note that your risk factors on page 11 relating to changes in
regulation and barriers to entry into the market place state that  certain regulations, fees or
restrictions may be imposed.  However, we note your extensive discussion of the specific
impact of various regulations on pages 47 – 51, including that you developed your Ultra-
low emissions technology in response to cert ain regulations in S outhern California.
Please note that this is just one example.  Please comprehens ively review and revise your
risk factors to tailor each risk factor so that  it addresses the specific  risks that impact your
business and presents such risks in a clear and concise manner.

5. We note your response to comment 14 of our le tter dated January 18, 2012.  We continue
to believe that you need to include a risk f actor addressing the poten tial risks relating to
John and George Hatsopoulos having little or  no continuing stake in the company, and
revise your risk factor on page 15 stati ng that you are controlled by a small group of
majority stockholders to reflect the fact that these stockholders have registered for resale

John N. Hatsopoulos Tecogen Inc. May24, 2012 Page 3

 100% of their holdings.  It is unclear from your response why there is  “essentially no risk
that John and George Hatsopoulos will sell a ll of their holdings.”  Given that the
shareholders are registering all of their holdings for resale, in  the event that the
registration statement is declared effective, th e shareholders would be able to sell all of
their holdings.  Please note, the amount bei ng registered for resale  must reflect a good
faith estimate of the amount that the selling s ecurity holders intend to sell.  To the extent
that John and George Hatsopoulos do not in tend to sell 100% of their holdings, please
revise accordingly.  Please advise.

Selling Security Holders, page 16

6. We note that in response to comment 15 of  our letter dated January 18, 2012 you state
that you have revised your disclosure to incl ude how the selling security holders acquired
the securities they may offer and sell pursuant to the registration statement, including the
dates of the transactions, the number of shar es purchased in each  transaction, and the
purchase price, if any.  However, we are unable to locate such disclosu re in this section.
Please advise and revise accordingly.
7. We note that in response to comment one  of our letter date d January 18, 2012 you
included an “Exhibit A” which you state lists each selling security holder, including the
number of shares registered on behalf of that shareholder on the S-1.  However, it is
unclear from Exhibit A and the disclosure provided on pages 19-21 which of the shares
listed in Exhibit A are being registered for resale.  For example, Exhibit A notes that
there are 303,223 shares owned by George Ha tsopoulos that are issuable upon future
exercise of a convertible debenture, but it is unclear whether Mr. Hatsopoulos is
attempting to register such shares for resale.  Please advise which of the shares listed in
Exhibit A are being registered, and ensure that your disclosure in this section accurately
reflects the shares being registered by each selling security holder.

Business, page 24

General

8. Please provide support for your statement on page 31 that “no other methodology for
obtaining this level of efficien cy gain exists or will ever  exist from power generation
sourced from fossil fuels.”  To the extent th at this statement is based on management’s
belief, please indicate that this is the case.  Alternatively, if the information is based on reports or articles, please provide  support for your statement.

9. Please provide us with copies of each source that supports your va rious qualitative and
quantitative statements in your disclosure, clearly marked to highlight the portion or
section that contains this information and cros s-reference it to the appropriate location in
your filing, as requested in comment 18 of our letter dated January 18, 2012.

John N. Hatsopoulos Tecogen Inc. May24, 2012 Page 4

 10. Please revise your disclosure here and in your  Prospectus Summary to clarify what you
mean by a low-cost “process of engine after treatment.”
11. We note your disclosure on page 24 that your principal generator suppliers are Danotek
Motion Technologies and Mara thon Electric, that you purch ase compressors from J&E
Hall International, and, as noted on page 30, you use a Ford engine for the Ilios heat
pump.  Please file agreements with these suppliers as exhibits to the registration
statement, or tell us why you are not required to do so.

12. We note you responses to comments 18 and 19 of our letter date d January 18, 2012, and
that you wish to keep certain footnotes in the Background section.  Further, we note that
you have significantly expanded your disc ussion under the Industry background section
and Business section so that you now include additional footnotes in your disclosure and
both these footnotes and the main text cont ain lengthy disclosure that includes highly
technical terms.  Please note th at your disclosure should co mply with the Plain English
requirements of Rule 421 of Regulation C.  Please delete the foot notes and revise your
disclosure throughout so that you avoid jargon and highly tec hnical terms and present the
relevant information in a clea r and concise manner.  For example, it does not appear that
detailed descriptions, such as the diffe rence between HHV and LHV, or a detailed
description of a permanent magnet synchronous generator, are helpful to an investor.
These are just examples and you should recons ider and revise the Business and Industry
sections in their entirety. Further, please de lete the references to external websites that
you include throughout your regist ration statement.  By including the URL or website
addresses, the information contained in the webs ite is treated as part  of the disclosure.
See
 SEC Release No. 33-7856 and SEC Releas e No. 33-7497 for additional guidance.

13. We note that in response to comment 23 of  our letter dated January 18, 2012, you have
indicated that you do not believe that your  business is dependent on American DG
Energy.  However, we note the significant am ount of your sales to American DG Energy
in 2010 and 2011, as disclosed in Note 13 to th e financial statements, and the fact that
you have entered into various agreements w ith American DG Energy indicating that you
will continue to do a notable amount of busine ss with American DG Energy in the future.
Based on your relationship with American  DG Energy, it is unclear why you do not
believe that you will have recurring revenue from American DG Energy.  Please advise.

Industry Background, page 25

Our Products and Services, page 30

14. We note your response to comment 27 of our letter dated January 18, 2012.  Given the
emphasis placed on each of your three products, we believe it is important for investors to
understand the contribution to revenues made  by each of your products.  Please revise
your disclosure accordingly.

John N. Hatsopoulos Tecogen Inc. May24, 2012 Page 5

 15. We note your disclosure on page 42 that you ha ve used the results of certain tests to
obtain an air permit exemption in New Jerse y.  Please revise your disclosure here, and
elsewhere as appropriate, to  explain why such a permit was required and whether you
will need similar permits to sell your products in other states or regions.

Distribution Methods, page 34

16. Please file any material agreements with distributors and outs ide sales agents and
representatives as exhibits to the registration statement.

17. We note that American DG Energy has exclusive sales representation rights to certain of
your products in New England, and that you pay a commission to American DG Energy
when you sell such products in New England.  Please disclose the amount of such commission, to the extent material, as we ll as any material impacts on your financial
operations.
18. Please disclose the purpose and or/intent of American DG Energy’s grant of sales
representation rights to its On-Site Utility en ergy service in Californi a.  In particular,
please explain what this energy se rvice is and what you intend to  use it for.  Please revise
your disclosure elsewhere, as appropriate.

Market Potential, page 35

Tecogen’s Strategy for Growth, page 38

19. Please revise or delete your disclosure thr oughout this section to eliminate repetitive,
highly technical and speculative disclosure.  The current disclosure is overly detailed,
complex and unclear.  To the extent that you wish to retain disclosure regarding the
market potential of CHP, please present it cl early and concisely, and consider including it
within another section of your prospe ctus, such as the Industry section.

Alliances, page 41

20. We note your revised disclosure in response to comment 32 of our letter dated January
18, 2012.  Please further revise you r disclosure to disclose th e dates of such alliances,
whether these are current alliances, and the sign ificance of such alliances.  Further, we
note that you state that you believe that “m ost” of these agreements are not material.
Please advise us as to which agreements are ma terial and please file such agreements as
exhibits to the registration statement.
21. We note your response to comment 33 of our letter dated January 18, 2012 that you do
not believe your exclusive licensing agreem ent with Wisconsin Alumni Research
Foundation is material because it “provide s for a $500 payment to the Foundation every
time [you] sell an InVerde system.”  It is un clear why this means that the agreement is

John N. Hatsopoulos Tecogen Inc. May24, 2012 Page 6

 not material.  In addition, we note that this  agreement covers the control software that
enables your microgrid system and allows your  products to be inte grated, and it appears
that the microgrid system is an important pa rt of your products.  Please file a copy of
your exclusive licensing agreem ent with the Wisconsin Alumni Research Foundation as
an exhibit to the registration statement or, alternatively, please explain why this
agreement is not material, including why a $500 payment for each InVerde system means
the agreement is not material.  See
 Item 601(b)(10) of Regulation S-K.

Competition, page 42

22. We note that your disclosure regarding your competitive position is overly detailed and
complex and it is unclear how some of the disc losure is relevant to  your company.  Please
comprehensively revise this section to pres ent a clear and concise description of the
competitive business conditions and your competitive position in the industry.

Certain Related Party Contracts, page 46

The Company and Its Affiliates, page 47

23. The disclosure contained in th ese sections appears to be dup licative of the disclosure in
the section entitled “Certain Relationships and Related Transactions.”  Please delete this
disclosure and consolidate your disclosure  under “Certain Relationships and Related
Transactions.”
Intellectual Property, page 47

24. Please disclose the duration of  your patents and licences.

Government Regulation, page 47

25. We note that your disclosure regarding your competitive position is overly detailed and
complex.  Further, we note that some of this disclosure appears to be phrased as a commentary on the industry standards, includ ing a historical overview, as opposed to a
concise description of the eff ects of government regulations.  For example, we note your
statement that “[t]he imposition of se emingly unreasonable standards by the SCAQMD
was not without warning nor arbi trary….”   Please comprehensiv ely revise this section to
present a clear and concise desc ription of the existing or pr obable effects of government
regulations on your business.  See
 Item 101(h)(4)(ix) of Regulation S-K.

John N. Hatsopoulos Tecogen Inc. May24, 2012 Page 7

 Management’s Discussion and Analysis of Financ ial Condition and Results of Operations, page
55

26. We note your revisions in res ponse to comment 47 of our letter dated January 18, 2012.
However, we note that your Overview section continues to appear to be largely identical
to the disclosure in your Prospectus Su mmary and in your Business section.  Your
MD&A Overview section should provide c ontext for the remainder of