This study involves the complete energy audit of the combined cycle 450 MW power plant. It includes a detailed energy balance and performance analysis of different cycle components that includes Gas Turbine, Steam Turbine and HRSG Unit. Firstly, Gas Turbine has been analysed as a single independent unit. Various parameters that affect its performance include the fuel GCV, compressor performance, and ambient air conditions etc. In this study, all such factors are examined for their effect on the overall plant performance. Secondly, Steam Turbines section has been examined which also includes the condenser and the entire feed water circuit. Lastly, HRSG unit is considered where an indirect method of energy balance has been employed, where prime focus would be at the various losses occurring during the run time. Heat losses have also been addressed which might occur due to insufficient or improper insulation of the entire instalment. In short, the prime purpose of this study is to evaluate the plant performance and pin point areas which require improvement