In this paper, the effect of fuel moisture on the efficiency of the IGCC is examined. The assumption, that the energy penalty of excess air compression can be reduced, by delivering lean syngas from the highly moist biomass gasification to the combustion chamber was considered. For this purpose, a theoretical model of the cycle was made. The results confirmed the expectations - the efficiency of the cycle increased with moisture content. The dependency was especially visible at higher operating pressures. (C) 2015 Elsevier Ltd. All rights reserved.