In this study, energy and exergy evaluation and parametric study were carried out using the actual operating parameters of a combined cycle power plant of 52MW having a dual pressure heat recovery steam generator (HRSG) using natural gas as a fuel located in Ankara city. The objective of this study is to investigate the energy and exergy flow of the power plant main units as well as the energy and exergy losses. Also, the present study investigates the effect of site conditions (ambient temperature, altitude) on the combined cycle power plant based on the first and second laws of thermodynamics. The results show that combustion chambers and HRSGs are the main sources of irreversibilities, accounting for 89% of the overall exergy losses. The total exergy loss and exergy efficiency of the plant is determined to be 68.599MW and 40.66%, respectively. (C) 2013 American Society of Civil Engineers.