Detailed IGCC coal power-plant thermo models, including different CO2 capture such as the chemical absorption MDEA and the hot potassium carbonate UNO Mk1, and the physical absorption Selexol are presented in this work. Based on these models, energy integrations are performed and IGCC efficiencies are compared for the cases with and without CO2 capture. For each CO2 capture system, different configurations are simulated in order to determine the best solutions in term of efficiency. The IGCC without capture yields an efficiency of 45.02%. The efficiency are closed for the IGCC with the MDEA and Selexol cases with 36.39% for the IGCC with MDEA capture and 36.42% for the IGCC with the Selexol capture system. The IGCC with the UNO process yields the highest efficiency with 37.33%. The UNO absorber can operate at higher temperature than the MDEA and Selexol cases. Therefore the water present in the syngas is not condensed before the absorber, thus the syngas mass-flow sending to the gas turbine is higher and the power produced in the gas turbine is, as well, higher. An overall Moo optimization is performed on the IGCC with the UNO CO2 capture system by varying different decision variables in the gasification, WGS, CO2 capture and gas turbine and cogeneration Rankine steam network units. The air pre-heat in the gas turbine has the most influence on the efficiency. By optimizing the different decision variables, an efficiency of 39.31% is yielded for the IGCC with the UNO CO2 capture for 90% of capture rate. In the prospect of resolving the best thermo-economic solution, an economic evaluation has to be performed in the future.