Phosphoric acid doped polybenzimidazole (PBI-poly[2,2’-(m-phenylene)-5,5’-bibenzimidazole]) has been investigated for use in a H-2/O-2 fuel cell. The prototype fuel cell test results show that the PBI fuel cell worked quite well at 150 degrees C with atmospheric pressure hydrogen and oxygen which were humidified at room temperature. No membrane dehydration was observed over 200h operating. The maximum power density of this prototype fuel cell was 0.25 W cm(-2) at current density of 700 mA cm(2). Further improvement of the cell performance is to be anticipated by properly impregnating the electrode structure with the polymer electrolyte. The advantage of the H-2/O-2 fuel cell using PBI as polymer electrolyte is that the cell design and the routine maintenance can be significantly simplified because of the low electro-osmotic drag number and good proton conductivity of the PBI membrane at elevated temperature.