In order to identify approaches for integrated gasification combined cycle (IGCC) plant optimization it is necessary to analyse where and why the losses in the process occur. Therefore a structured exergy analysis of an IGCC with carbon capture was performed to identify losses on a plant, subsystem and individual component level. The investigation of the IGCC base case revealed an exergetic efficiency of 40%. Thus, 60% of the whole fuel exergy is lost in the process. On the subsystem level it was found that the major loss contributor is the combined cycle followed by the gas treatment section and the gasification island. Furthermore, it was demonstrated that the significance of the losses is higher in upstream processes than in downstream processes. On the individual component level it is shown that 80% of all exergy losses in the plant are caused by just 4 components. Since two of them are related to the gas conditioning an advanced hot gas clean-up (HGCU) system was proposed which improves exergy efficiency of the IGCC plant by 5.2%-points. However, assuming an ideal IGCC process an exergy efficiency of 54.1% was calculated demonstrating significant potential for further optimization of the technology. (C) 2011 Elsevier Ltd. All rights reserved.