Performance effects of proton exchange membrane fuel cell (PEMFC) at various temperatures of the gases feeding the electrodes were investigated. Experiments have been carried out on two different homemade PEMFCs with hydrogen/oxygen and hydrogen/air feed. On each PEMFC with different feed that have an active area of 9 cm(2) Nafion (TM) NE-1035 as proton exchange membrane (PEM) and electrodes with platinum load of 0.9 mg/cm(2) were used. Temperature of humidified gases in 1 atm pressure that feed the PEMFCs kept at ambient temperature (25 degrees C) varies from ambient temperature to 95 degrees C by 10 degrees C step. During the experiment backpressures of each type of the PEMFCs held constant at 1 atm and the external load resistance (R-L) varies from 0 to 1000 K Omega. In high temperatures the diffusivity of gases increase and mass transport resistance decrease. However, the ion-conductivity of the PEM in ohmic region increases. As a result it was concluded that performance of the PEMFCs depends on the concentration of gases and on the discharge of water (H2O) content formed by electro-chemical reactions.