It is known that different operating conditions influence the performance of the proton exchange membrane fuel cell. The effects of different humidification temperatures, backpressures, and flow rates of the reactant gases on the performance of the proton exchange membrane fuel cell have been studied experimentally. Results are presented in the form of I-V polarization curves. The possible mechanisms and their interrelationships for these results are discussed. Commonly it can be said that the electrochemical reaction rate have to be controlled at its maximum rate. Because, excessive use of required operating conditions cause "flooding" this in turn decreases the electrochemical reaction. In this context, the optimum working conditions under the cell temperature of 70 degrees C were found to be as follows: anode humidification temperature of 75 degrees C; cathode humidification temperature of 90 degrees C; backpressures of 3atm on both sides, and flow rates of 40cm(3)/min on both sides. Under these conditions, the amount of the maximum power density was determined as 0.727 W/cm(2).