The steady state conditions in an autohumidification STR PEM fuel cell were determined as functions of temperature from 35 to 105 ◦C and load resistances from 0.5 to 15 . In each test the fuel cell was conditioned by setting the temperature, reducing the load resistance to 0.5 , and permitting the fuel cell to stabilize for > 2 h. The load resistance was then set to the desired value and the fuel cell was allowed to stabilize for > 4 h. The current through the external load, voltage across the external load, temperature of the fuel cell and relative humidity of the anode and cathode effluents were recorded.