2 February 2009

Gran Tierra Energy Announces Addition of Chief Operating Officer to Executive Team

Breadth of Management Expanded with Addition of International E&P Veteran, Shane O’Leary

CALGARY, Alberta – February 2, 2009 – Gran Tierra Energy Inc. (NYSE Alternext: GTE; TSX: GTE), a company focused on oil exploration and production in South America, today announced that Shane P. O’Leary will be joining the company as Chief Operating Officer effective March 2, 2009. Mr. O’Leary, whose regional experience includes South America, North Africa, the Middle East, the former Soviet Union, and North America, will be based out of the Calgary corporate head office and report to Dana Coffield, the company’s President and Chief Executive Officer.

Prior to joining Gran Tierra Energy, Mr. O’Leary was President and Chief Executive Officer of First Calgary Petroleums Ltd., an oil and gas company actively engaged in exploration and development activities in Algeria. From 2002 to 2006, Mr. O’Leary worked for Encana Corporation where his positions included Vice President of Development Planning and Engineering, as well as Vice President Brazil Business Unit. From 1985 to 2002 he worked for the Amoco Production Company/BP Exploration where he occupied numerous senior finance, planning, and business development positions with assignments in Canada, U.S.A., Azerbaijan and Egypt, culminating in his role as Business Development Manager for BP Alaska Gas.   Early in his career Mr. O’Leary worked as a Corporate Banking Officer for Bank of Montreal’s Petroleum group in Calgary, a Reservoir Engineer for Dome Petroleum, and as a Senior Field Engineer for Schlumberger Overseas, S.A. in Kuwait.

Commenting on the addition to the executive team, Mr. Coffield stated, “It is with great pleasure that the Board of Directors makes today’s announcement. Shane brings over 30 years of international oil and gas experience in operations, finance, planning, and business development to our group. The breadth and depth of his global experience is perfectly complementary with the business strategy of the company and we expect that he will play a significant role in supporting the continued growth of our company.”

Mr. O’Leary, 52, earned his Bachelor of Science degree in chemical engineering from Queen’s University in Kingston, Ontario and his Masters in Business Administration from the University of Western Ontario in London, Ontario. He is a member of the Canadian National Committee of the World Petroleum Council and The Association of Professional Engineers, Geologists, and Geophysicists of Alberta (P. Eng).

About Gran Tierra Energy Inc.

Gran Tierra Energy is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada and incorporated in the United States. The company holds interests in producing and prospective properties in Colombia, Argentina and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Gran Tierra Energy trades on the NYSE Alternext under the symbol “GTE” and on the Toronto Stock Exchange under the symbol “GTE”.

Additional information concerning Gran Tierra Energy is available at www.grantierra.com , on SEDAR (www.sedar.com) and with the Securities and Exchange Commission (www.sec.gov).

Forward Looking Statements

The statements in this press release regarding Gran Tierra Energy’s expectations regarding continued growth are “forward-looking statements” within the meaning of the U.S. federal and Canadian securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the U.S. Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results or outcomes to differ materially from those contemplated by the forward-looking statements. Although, Gran Tierra Energy believes that the assumptions underlying, and expectations reflected in, these forward-looking statements are reasonable, it can give no assurance that these assumptions and expectations will prove to be correct.

Factors that could cause results to differ materially from those described in the forward-looking statements include: Gran Tierra Energy’s operations are located in South America, and unexpected problems can arise due to additional strikes, guerilla activity, technical difficulties, operational difficulties and weather conditions which impact operations, including the exploration, production, transportation or sale of oil and gas; heightened unrest in Colombia could imperil the safety and security of Gran Tierra Energy’s assets and personnel despite the safety measures Gran Tierra Energy has put in place to address the current situation, which could also delay the testing and drilling and could also impact production; and those other risks found in the periodic reports filed by Gran Tierra Energy with the United States Securities and Exchange Commission, including in the section entitled “Risk Factors” in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 6, 2008, and available at the Securities and Exchange Commission’s internet site www.sec.gov and on SEDAR at www.sedar.com.

All forward-looking statements in this press release are expressly qualified by information contained in each company’s filings with regulatory authorities and, subject to its obligations under applicable securities laws, Gran Tierra Energy does not undertake to publicly update forward-looking statements, whether as a result of new information, future events or otherwise.