16 May 2013

Gran Tierra Energy Announces Successful Acreage Awards in Brazil

Expands Land Position in Recôncavo Basin With Successful bids on Three Blocks in ANP Bid Round 11

CALGARY, Alberta, May 16, 2013, Gran Tierra Energy Inc. (NYSE MKT: GTE, TSX: GTE), a company focused on oil exploration and production in South America, today announced successful bids on three blocks in the recently completed 2013 Brazil Bid Round administered by Brazil’s Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (“ANP”). The open and competitive process was available to those pre-qualified by the ANP and successful bid contracts are expected to be finalized by August, 2013.“Gran Tierra Energy has made a commitment to building a business in Brazil, initially by successfully developing the Tiê conventional oil discovery in the onshore Recôncavo Basin, growing production from approximately 400 barrels of oil per day gross, to approximately 1,000 barrels of oil per day gross currently,” said Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy Inc. “In addition, we have initiated a new technology application in Brazil, horizontal drilling with multi-stage fracture stimulation in tight oil-bearing reservoirs. We are extremely pleased to have successfully captured three new blocks which significantly increases the acreage we have to refine the technology and pursue this play in the coming years in the event of success.”

The three blocks, REC-T-86, 117 and 118, are located north of Gran Tierra Energy’s core existing areas in the Recôncavo Basin onshore Brazil and offers additional potential on the company’s current exploration play trend that will enable Gran Tierra Energy to leverage its growing knowledge of the basin. The three blocks encompasses 20,658 gross acres of land under an initial 3 year exploration period, during which Gran Tierra Energy is committed to drill 5 exploration wells, acquire 84 square kilometers of 3D seismic data and pay a signature bonus of approximately $16.5 million upon finalization of the concession agreement.

About Gran Tierra Energy Inc.

Gran Tierra Energy is an international oil and gas exploration and production company, headquartered in Calgary, Canada, incorporated in the United States, trading on the NYSE MKT (GTE) and the Toronto Stock Exchange (GTE), and operating in South America. Gran Tierra Energy holds interests in producing and prospective properties in Colombia, Argentina, Peru, and Brazil. Gran Tierra Energy has a strategy that focuses on establishing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth.

Gran Tierra Energy’s Securities and Exchange Commission filings are available on a web site maintained by the Securities and Exchange Commission at http://www.sec.gov and on SEDAR at http://www.sedar.com.

Forward Looking Statements and AdvisoriesThis news release contains certain forward-looking information, forward-looking statements and forward-looking financial outlook (collectively, “forward-looking statements”) under the meaning of applicable securities laws, including Canadian Securities Administrators’ National Instrument 51-102 – Continuous Disclosure Obligations and the United States Private Securities Litigation Reform Act of 1995. The use of the words “expected”, “will”, and “potential” identify these forward-looking statements. These forward-looking statements are regarding: the expected finalization date of the bid contracts; and the application of technology in the Recôncavo Basin.The forward-looking statements contained in this news release 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, including, among others: the primary risk of regulatory or other delays in finalizing the bid contracts by August, 2013, which could cause the finalization of the bid contracts to be delayed or not to occur at all; Gran Tierra Energy’s operations are located in South America, and unexpected problems can arise due to guerilla activity, technical difficulties, operational difficulties which could impact its time schedule for acquiring seismic data and testing and drilling operations; geographic, political and weather conditions can impact testing and drilling operations; the risk that seismic data acquired may not provide the type of information that Gran Tierra Energy expects, which could cause Gran Tierra Energy existing knowledge of the Recôncavo Basin to not be as useful as Gran Tierra Energy expects; and the risk that current global economic and credit market conditions may impact oil prices and oil consumption more than Gran Tierra Energy currently predicts, which could cause Gran Tierra Energy to modify its exploration activities. Further information on potential factors that could affect Gran Tierra Energy are included in risks detailed from time to time in Gran Tierra Energy’s Securities and Exchange Commission filings, including, without limitation, under the caption “Risk Factors” in Gran Tierra Energy’s Quarterly Report on Form 10-Q filed May 6, 2013. These filings are available on a Web site maintained by the Securities and Exchange Commission at http://www.sec.gov and on SEDAR at www.sedar.com. The forward-looking statements contained herein are expressly qualified in their entirety by this cautionary statement. The forward-looking statements included in this press release are made as of the date of this press release and Gran Tierra Energy disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as expressly required by applicable securities legislation.

Contact Information

For investor and media inquiries please contact:

Jason Crumley

Director, Investor Relations