To investigate the effect of liquid water saturation on the efficiency of polymer electrolyte fuel cells, it is important to determine the exact relationship between the liquid water saturation profile and other parameters. In this paper, the pore size distribution (PSD) is used to calculate the liquid water saturation in a fuel cell. Using the PSD, liquid water saturation is calculated from experimental data for the capillary pressure on a porous media. Numerical analysis is used to analyze and evaluate the liquid water pressure and temperature profiles in a fuel cell. This paper uses two-phase, three-dimensional analysis to determine the effects of using the PSD.