Life test of the proton exchange membrane fuel cell (PEMFC) was carried out at a current density of 160 mA cm(-2). After an operation up to 2250 h, the performance of the single PEMFC shown by a currenttime curve did not decay significantly. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize both anodic and cathodic catalysts before and after the life test. Cyclic voltammetric (CV), polarization, and power density curves were plotted with the cell at different periods during long-term operation. The results showed that the electrochemically active surface areas (SEAS) of anodic and cathodic catalysts firstly increased, and then decreased with the operation time. The SEAS loss of anodic catalyst was evidently smaller than that of cathodic one. The thickness of Nafion (R) film decreased with working time as shown by SEM. The particle size of cathodic Pt/C catalyst was evidently bigger than that of anodic one. The degradation of cathodic catalyst for oxygen electroreduction was one of the main factors affecting the performance decay of PEMFC. (C) 2008 Elsevier B.V. All rights reserved.