Calpine Corporation (NYSE: CPN) has agreed to supply electric generation capacity and power to American Electric Power Service Corporation (NYSE: AEP), as agent for Public Service Company of Oklahoma (PSO), from Calpine’s Oneta Energy Center (Oneta) from June 1, 2016, through May 31, 2031. Under the contract, PSO will purchase 260 megawatts of Oneta’s capacity, energy and ancillary services. PSO will have the right to dispatch Oneta to meet its energy needs up to the contracted capacity. Calpine secured the contract through a competitive process resulting from a request for proposals that PSO issued earlier this year. “We are pleased to partner with PSO to provide Oklahomans with power that is generated locally from cleaner burning natural gas produced in Oklahoma,” said Thad Hill, Calpine’s Chief Operating Officer. “The highly efficient Oneta Energy Center is one of the most in-demand assets in Calpine’s fleet. When this 15-year power purchase agreement takes effect, Oneta’s capacity will be almost fully subscribed for the balance of the decade at pricing levels that reflect the tightening reserve margins in the region.” The clean and modern Oneta Energy Center is located near Tulsa in Coweta, Oklahoma. This combined-cycle, natural gas-fired power plant is capable of generating up to 1,134 megawatts of electricity. PSO is an electric utility company serving more than 530,000 customers in eastern and southwestern Oklahoma. With headquarters in Tulsa, PSO provides electricity to 230 cities and towns across a service area encompassing 30,000 square miles. The contract is conditioned on certain approvals from the Oklahoma Corporation Commission and on securing satisfactory transmission service. About Calpine Calpine Corporation is the largest independent power producer in the U.S., with a fleet of 93 power generation plants representing more than 28,000 megawatts of generation capacity. Last year our plants generated more than 94 million megawatt hours of power for our wholesale customers in 20 states and Canada. Our 91 operating plants as well as two under construction consist primarily of natural gas-fired and renewable geothermal power plants that use advanced technologies to generate power in a low-carbon and environmentally responsible manner. Our modern, clean, efficient and cost-effective fleet stands ready to respond to the increased need for cleaner and more affordable power as the economy recovers, as new environmental rules are implemented and force older, dirtier plants to retire or reduce generation, as variable renewable power generation from wind and solar grows and with it the need for flexible natural gas generation to assure firm supply to the grid, and finally, as natural gas becomes economically competitive with coal as a fuel for power generation. Please visit www.calpine.com to learn more about why Calpine is a generation ahead - today. Forward-Looking Information In addition to historical information, this 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, as amended. Words such as “believe,” “intend,” “expect,” “anticipate,” “plan,” “may,” “will” and similar expressions identify forward-looking statements. Such statements include, among others, those concerning expected financial performance and strategic and operational plans, as well as assumptions, expectations, predictions, intentions or beliefs about future events. You are cautioned that any such forward-looking statements are not guarantees of future performance and that a number of risks and uncertainties could cause actual results to differ materially from those anticipated in the forward-looking statements. Please see the risks identified in this release or in Calpine’s reports and registration statements filed with the Securities and Exchange Commission, including, without limitation, the risk factors identified in its Annual Report on Form 10-K for the year ended Dec. 31, 2011. These filings are available by visiting the Securities and Exchange Commission’s website at www.sec.gov or Calpine’s website at www.calpine.com. Actual results or developments may differ materially from the expectations expressed or implied in the forward-looking statements, and Calpine undertakes no obligation to update any such statements.