Gas/steam combined cycle, which is a synergetic integration of Brayton cycle-based gas turbine cycle (topping cycle) and Rankine cycle based steam turbine cycle (bottoming cycle), uses the exhaust heat from the gas turbine to increase the power plant output and boost the overall efficiency. The gas/steam combined cycle performance is mainly influenced by the performance of the gas turbine cycle. The efforts are being made for further enhancement in the performance of the gas turbine cycle. Amongst several performance augmentation methods, the rise in cycle pressure ratio (CPR) and turbine inlet temperature (TIT) have a prominent influence on the performance of the GT cycle. Present book deals with thermodynamic modelling and analysis of the thermodynamic performance of gas turbine cycle and gas/steam combined cycle with different methods of inlet air cooling (IAC), steam injection (SI) and film cooling (FC) of the gas turbine blade. The parameters for performance evaluation include specific work output, overall thermal efficiency and specific fuel consumption.