In this study, exergy and sensitivity analysis of a combined cycle gas turbine (CCGT) power plant in Ankara, Turkey, is performed with real plant data sets. Exergy efficiency of each component and overall plant is determined by calculating exergy destructions. In addition, a sensitivity analysis is carried out by changing some critical parameters of the cycle. The effects of parameters on exergy efficiency, CO2 emissions of the plant and heat transfer area is presented. The total exergy destruction and net exergy efficiency of the plant is calculated 228.05 MW and 50.11 % respectively. Exergy analysis shows that the major exergy destructions take place in combustion chamber with the value of 124.07 MW and 54.41% of the total exergy destruction of the overall plant. The effect of ambient temperature, duct burner exhaust temperature, steam injection mass flow rate, steam turbine inlet pressure, high pressure and low pressure evaporator pinch point temperature difference, high pressure and low pressure economizer sub cooling temperature are examined by sensitivity analysis. The variation of exergy efficiency, CO2 emissions and heat transfer areas are given.