The damage caused by cell reversal during proton exchange membrane fuel cells (PEMFCs) operation with air starvation was investigated by a single-cell experiment. Samples from degraded membrane-electrode assemblies (MEAs) were characterized. The loss of electrochemical surface area of the cathode platinum was detected by in situ cyclic voltammetry, and platinum sintering was detected by transmission electron microscopy (TEM) analysis. Degradation at the anode was not detected in the chemical analysis of the anode catalyst layer of MEA samples by energy dispersive X-ray analysis (EDX) and TEM. An obvious decrease in the performance of PEMFC was observed in a sample degraded by cell reversal for 120 min. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.