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VIA EDGAR

January 17, 2013

Mr. Brad Skinner

Senior Assistant Chief Accountant

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549-3628

 Re: Gran Tierra Energy Inc.

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

Filed February 27, 2012

File No. 001-34018

Dear Mr. Skinner:

On behalf of Gran Tierra Energy
Inc. (“Gran Tierra” or the “Company”) we are responding to the comment (the
“Comment”) received from the staff (the “Staff”) of the Securities and Exchange
Commission (the “Commission”) by letter dated January 9, 2013, with respect to Gran Tierra’s Form
10-K listed above (the “2011 Form 10-K”). The Comment has, for the Staff’s convenience, been set
forth below in this response letter.

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

Proved Undeveloped Reserves,
page 18

1.
We note your response to comment one which indicates that you converted 3.9 MMBOE of proved undeveloped
reserves and added 4.6 MMBOE of PUDs in Colombia. Please quantify the amount of investments to convert the 3.9 MMBOE and tell us
how you expect to comply with Item 1203 of Regulation S-K.

Response:

During the year ended December
31, 2011, Gran Tierra incurred capital expenditures of $28.8 million associated with the development of proved undeveloped reserves
(“PUDs”) in Colombia. Given that both Costayaco and Moqueta were not mature fields and appraisal and development
activities were undertaken throughout 2011 which provided new information about the reservoir size and performance, work performed
resulted in reserve additions across all categories, including PUDs.  Specifically, the investments made with respect to PUDs
in 2011 both resulted in a movement from PUDs to proved producing reserves and increased PUDs through an increase in the estimated
reservoir size.

Gran
Tierra expects to satisfy the Item 1203(c) of Regulation S-K disclosure requirement in its Form 10-K for the year ended
December 31, 2012 (the “2012 Form 10-K”), by disclosing the amount of 2012 investments made,
including but not limited to capital expenditures, associated with the development of PUDs, the fields to which these
expenditures related and the nature of development activity undertaken to convert PUDs to proved developed reserves.

    300, 611-10th Avenue SW, Calgary, Alberta, Canada
    (403) 265-3221 Fax (403) 265-3242
    www.grantierra.com

The Company
intends to include disclosure of the following type of information in its 2012 Form 10-K using 2011 related information for example
purposes:

“At December 31,
2011, we had total proved undeveloped reserves NAR of 8.2 MMBOE (December 31, 2010 – 4.1 MMBOE), including 4.6 MMBOE
in Colombia (December 31, 2010 – 3.9 MMBOE), 3.3 MMBOE in Argentina (December 31, 2010 – 0.2 MMBOE) and 0.3
MMBOE in Brazil (December 30, 2010 – nil). Approximately 38% of proved undeveloped reserves are located in our Puesto
Morales field in Argentina. This field was acquired as a result of the Petrolifera acquisition in 2011. Additionally, approximately
37% and 15% of proved undeveloped reserves are in our Moqueta and Costayaco fields in Colombia. None of our proved undeveloped
reserves at December 31, 2011, have remained undeveloped for five years or more since initial disclosure as proved reserves
and we have adopted a development plan which indicates that the proved undeveloped reserves are scheduled to be drilled within
five years of initial disclosure as proved reserves.

Significant
changes in proved undeveloped reserves are summarized in the table below:

    Oil Equivalent

  (MMBOE)

    Balance, December 31, 2010

    4.1

    Purchases

    3.8

    Discoveries and extensions

    1.6

    Converted to proved

    (4.0)

    Technical revisions

    2.7

    Balance, December 31, 2011

    8.2

In 2011,
we converted 4.0 MMBOE proved undeveloped reserves to proved developed status. Approximately 100% of proved
undeveloped reserves conversions occurred in the Costayaco and Moqueta fields in Colombia. In 2011, we made investments,
consisting solely of capital expenditures, of $28.8 million in Colombia associated with the development of proved undeveloped
reserves. The majority of proved undeveloped conversions occurred as a result of ongoing development activities in the
Costayaco and Moqueta fields, including infill drilling and a pressure maintenance project in the Costayaco field and infill
drilling and facilities development in the Moqueta field.”

Please do not
hesitate to call me at (403) 265-3221, ext. 2223, if you have any questions or would like any additional information regarding
this matter.

    -2-

    Sincerely,

    Gran Tierra Energy Inc.

    By:
    /s/ James Rozon

    James Rozon

    Chief Financial Officer

    cc:
    Dana Coffield – Chief Executive Officer and President

    Nancy H. Wojtas, Esq.

    -3-