In the HAT cycle, as the absolute humidity of the moist combustion gas increases.. the performance of the turbine will also change. In this paper, one model to calculate the thermodynamic properties of the moist combustion gas is introduced, and another model to calculate the performance Of the turbine is formulated based on the equations of one dimensional flow. Using these models with the geometric parameters of the turbine fixed, at the design working condition.. the performance of the turbine is calculated and analyzed for different absolute humidities. Finally.. some conclusions about the turbine performance are presented. (C) 2004 Elsevier Ltd. All rights reserved.