This is Describes about the Operational Aspects of Combined Cycle Power Plant, Main concentration is on Performance Analysis and Thermodynamic aspects of all the sub systems. The effective heat utilization and accounting of Exergy in the work consumable devices and work extractable. The improvement aspects of various power plants based on combined cycle has been discussed. This book contains the information regarding the working, improving the efficiency of a combined cycle power plant through exergy analysis. In the combined cycle power plants,natural gas is used as major fuel. These plants can achieve higher efficiency in converting fuel to electricity which makes it possible for relatively high priced fuel like natural gas to be competitive for intermediate or base loads.