Combined Cycle Gas Turbines (CCGT) play a major role in Power generation since they combine the Gas turbine cycle with the Steam Turbine cycle which are capable of reaching efficiencies as high as 60 %. This publication looks at the thermodynamic and engineering approach based on the first and second laws of thermodynamics, and is adopted in the development of a mathematic model using Microsoft Excel program for the design of the Compressor, Combustor, gas turbine and steam turbine as well as determining the overall efficiency and power generation capacities. The model generates actual...