14 December 2005

Gran Tierra Energy Announces Progress in Oil Drilling Operations

CALGARY, Alberta, Dec. 14 /CNW/ – Gran Tierra Energy, Inc. (OTC Bulletin Board: GTRE) today announced progress in the drilling of the Ramon Lista-1001 well located approximately 10 kilometers north-west of the Palmar Largo Field in the Noroeste Basin of Argentina. Gran Tierra holds a 14% interest in the Palmar Largo Joint Venture, currently producing approximately 340 barrels per day (net before royalties) to the Company. Ramon Lista-1001 was spudded on September 25, 2005. Its primary objective is the Palmar Largo Formation, the major producing horizon of the Palmar Largo Field. An upper member of the Yacoraite Formation, the Puesto Guardian, is a secondary objective. The total depth is projected to be 4,330 meters. At this time the well has reached 4,028 meters and a 9-7/8 liner has now been installed. It is expected that the well will reach the total depth by mid-December and testing of the primary target is expected by early January.

About Gran Tierra Energy, Inc.

Gran Tierra Energy, Inc. is an international oil and gas exploration and production company, headquartered in Calgary, Canada, incorporated and traded in the United States and operating in South America. The Company currently holds interests in producing and non-producing properties in Argentina and is pursuing a growth strategy that focuses on establishing a portfolio of producing properties, development and exploration opportunities and land, by selective acquisitions, to provide a base for future growth. Additional information concerning Gran Tierra is available at http://www.grantierra.com.

Forward Looking Statements

This press release contains ‘forward-looking statements’ within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, including without limitation those statements regarding the Company’s ability to exploit oil and gas exploration opportunities. These statements are expressed in good faith and based upon a reasonable basis when made, but there can be no assurance that these expectations will be achieved or accomplished. Although the forward-looking statements in this release reflect the good faith judgment of management, forward-looking statements are inherently subject to known and unknown risks and uncertainties that may cause actual results to be materially different from those discussed in these forward-looking statements including, but no limited to, failing to discover reserves that may be extracted on a commercially viable basis, inaccurately estimating oil and gas reserves, intense competition, environmental risks and general economic conditions including the price of oil and gas. Readers are urged not to place undue reliance on these forward-looking statements, which speak only as of the date of this release. We assume no obligation to update any forward-looking statements in order to reflect any event or circumstance that may arise after the date of this release, other than as may be required by applicable law or regulation. Readers are urged to carefully review and consider the various disclosures made by us in the our reports filed with the Securities and Exchange Commission, including those risks set forth in the Company’s Current Report on Form 8-K filed on November 10, 2005, which attempt to advise interested parties of the risks and factors that may affect our business, financial condition, results of operation and cash flows. If one or more of these risks or uncertainties materialize, or if the underlying assumptions prove incorrect, our actual results may vary materially from those expected or projected. We undertake no obligation to update these forward looking statements.