The scope of these guidelines includes fossil-fueled power plants, gas-turbine power plants operating in combined cycle, and the balance-of-plant portion including interface with the nuclear steam supply system of nuclear power plants. The guidelines include performance monitoring concepts, a description of various methods available, and means for evaluating particular applications. The guidelines provide procedures for validation and interpretation of data, determination of performance characteristics and trends, determination of sources of performance problems, analysis of the performance in relation to the process, determination of losses due to degradation, possible corrective actions, and performance optimization. The guidelines provide the necessary information for implementing a performance monitoring program, using either an automated or a manual data acquisition system, or both.