Many factors, such as mole fractions of oxygen and hydrogen, help improve the performance of proton exchange membrane fuel cells. The variation of mole fractions can be achieved by changing the operating pressure and relative humidity of the fuel cells. The changes in operating conditions are directly related to the electrochemical reaction and water generation of the fuel cells. The geometrical shape of the fuel cells also should be considered a factor in predicting performance because this affects the species' reaction speed and distribution. The current study considers four geometrical cell shapes with varied lengths and electrode and gas channel numbers. The variation in inlet pressure is considered in analyzing the current density distribution of the fuel cells and, subsequently, of liquid water generation. A serpentine gas flow channel is assumed, and its two-dimensional arrangement is considered in the different gas channel numbers and its length. Four inlet pressure variations and four geometrical shape variations also are considered in analyzing the fuel cells' current density and water generation distributions. The results obtained from this research can be utilized in identifying the fuel cells' optimal operating pressure and designing their gas channel number and arrangement. Copyright (c) 2011 John Wiley & Sons, Ltd.