The new edition of PTC 22 is intended to be a more thorough and accurate approach to the thermal performance testing of gas turbines based on industry feedback and harmonization with other codes and standards. To more completely support testing of gas turbines in a broad range of applications, this edition includes significant changes from previous to incorporate methodology for determination of gas turbine exhaust energy, flow, and temperature. PTC 22 establishes directions and rules for conduct and results reporting of thermal performance tests for open cycle gas turbine power plants and gas turbine engines. This performance test code provides explicit instruction on determining corrected power, heat rate, exhaust flow, exhaust energy, and exhaust temperature. Guidance is also provided for designing testing requirements and programs to satisfy different goals such as absolute performance and comparative performance. It is the intent of this performance test code to provide results with the highest level of accuracy consistent with the best engineering knowledge and practice in the gas turbine industry. In planning the test, an uncertainty analysis must demonstrate that the proposed instrumentation and measurement techniques meet the requirements of the Code. PTC 22 is used in power plants worldwide and is recognized internationally. This performance test code was developed by a committee with balanced membership from manufacturers, power plant owners and operators, design engineers, and general interest groups.