A carbon-supported non-noble metal catalyst, Fe-N/C,was used as the cathode catalyst to construct membrane electrolyte assemblies (MEAs) for a proton exchange membrane (PEM) fuel cell. The performance of such a fuel cell was then tested and diagnosed using electrochemical impedance spectroscopy (EIS) in the temperature range of 23-8 degrees C. Based on the EIS measurements, individual resistances, such as charger transfer resistance and membrane resistance, were obtained and used to simulate polarization curves (current-voltage (I-V) curves). A close agreement between the simulated I-V curves and the measured curves demonstrates consistency between the polarization and EIS data. The temperature-dependent parameters obtained via EIS, such as apparent exchange current densities and electrolyte membrane conductivities. were also used to acquire activation energies for both the oxygen reduction reaction (ORR) catalyzed by an Fe-N/C catalyst and the proton transport process across the electrolyte membrane. In addition, the maximum power densities for such a fuel cell were also analyzed. (C) 2008 Elsevier Ltd. All rights reserved.