A high-temperature proton exchange membrane (PEM) fuel cell using H3PO4-doped poly benzimidazole (PBI) as solid polymer electrolyte has been developed and tested. The influences of operating temperature (between 130 and 170 °C), operating pressure (between 0 and 2 bar), and air flow rate on the performances of the fuel cell have been measured. A maximum power density of ca. 200 mW/cm2 has been measured. The existence of an optimum air flow rate (expressed in oxygen stoichiometric ratio) has been put into evidence. It allows an increase of the fuel cell voltage from 250 mV up to ca. 400 mV at 0.4 A/cm2.