Integrated gasification combined cycle (IGCC) power plants have become more attractive after the emission regulations of the thermal power plants. IGCC power plants enable to control emissions which cause global warming. Low grade lignites, biomass and wastes can be utilized by this technology. This study deals with the thermodynamic analysis of an IGCC power plant. Energy and exergy analysis are carried out for a Texaco type gasifier, one stage, oxygen blown and slurry fed. Cold gas cleaning (fuel gas treatment) system is considered for the simulations, performed in THERMOFLEX software. A parametric study is also carried out to show the effects of the O-2 purity, fuel supply temperature, gasifier temperature and H2O content of the slurry to the IGCC performance. Net power and net electric efficiency are calculated to be 389.669 MW and 43.53% respectively. Exergy efficiency of the simulated IGCC is found to be 40.36% and the highest exergy destruction is observed in gasifier and the combustion chamber of the gas turbine.