SecProbe.io

September 2 4, 2012

Via E -Mail
Mr. James Rozon
Chief Financial Officer
Gran Tierra Energy Inc.
300, 625 11 th Avenue SW
Calgary, Alberta
Canada T2R 0E1

Re: Gran Tierra Energy Inc.
 Form 10-K for Fiscal Year Ended December 31, 2011
Filed February 27, 2012
File No.  1-34018

Dear Mr. Rozon :

We have reviewed your filing an d have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand your
disclosure.

Please respond to this letter within ten business days by amending your filing, by
providing the requested information, or by advising us when you will provide the requested
response.   If you do not believe our co mments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.

After reviewing any amendment to your filing and the information you provide in
response to these  comments, we may have  additional comments.

Form 10 -K for the Fiscal Year Ended December 31, 2011

Proved Undeveloped Reserves, page 18

1. Your disclosure under this section indicates that proved undeveloped reserves in
Argentina increased during 2011 as a result of the Petrolifera acquisition, and that proved
undeveloped reserves in the Moqueta and Costayaco fileds in Colombia did not change
materially during 2011.   This implies that you did not convert material amounts of proved
undeveloped reserves to proved developed during the year.   Supplementally, tell us the
volume of provide undeveloped reserves converted to proved developed during the
year.   Additionally, tell us how the volume of proved undeveloped reserves converted to
proved developed during the year compared to your development plans as of the
beginning of the year.

Mr. James Rozon
Gran Tierra Energy Inc.
September 2 4, 2012
Page 2

2. Your disclosure under this section indicates that all your proved undeveloped reserves are
scheduled for development within five years.   Confirm to us that, for all your proved
undeveloped rese rves, a development plan has been adopted which indicates that the
reserves are scheduled to be drilled within five years of initial booking as proved
reserves.   For any proved undeveloped reserves not schedule to be drilled within five
years of initial bo oking, describe the specific circumstances which justify a longer
time.   See Compliance and Disclosure Interpretation 131.04 for information regarding
what constitutes adoption of a development plan.   See Compliance and Disclosure
Interpretations 108.01 an d 131.03 for information regarding “development projects” and
“specific circumstances”.

3. Send us, as supplemental information, a reconciliation of beginning and ending provide
undeveloped reserves for the years ending December 31, 2010 and 2011.   The
reconciliation should include beginning and ending balances, as well as changes during
the year attributable to purchases, sales, discoveries and extensions and provide
undeveloped reserves converted to proved.

Supplementary Data,   page 81

Reserve Quantit y Information, page 81

4. Revise to include net quantities of proved undeveloped reserves of oil and gas for all
periods presented.   Refer to ASC 932 -235-50-4.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Exchange Act of
1934 and all applicable Exchange Act rules require.   Since the compa ny and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.

 In responding to our comments, please provide  a written statement from the co mpany
acknowledging that:

 the company is responsible for the adequacy and accuracy of the disclosure in the filing;

 staff comments or changes to disclosure in response to staff comments do not foreclose
the Commission from taking any action with respect to the filing; and

 the company may not assert staff comments as a defense in any proceeding initiated by
the Commission or any person under the federal securities laws of the United States.

Mr. James Rozon
Gran Tierra Energy Inc.
September 2 4, 2012
Page 3

 You may contact John Cannarella at (202) 551 -3337 if you have q uestions regarding
comments on the financial statements and related matters.    Please contact me at (202) 551 -3489
with any other questions.

Sincerely,

        /s/ Brad Skinner

        Brad Skinner
        Senior Assistant Chief Accountant