The high power density and rapid adjustment to power demands make proton exchange membrane fuel cells (PEMFCs) one of the best candidates for a clean alternative energy sources for the 21st century. Analytical and experimental works have been presented in this paper to investigate a single PEMFC. These include a study of PEMFC performance, the effects of operating temperature and pressure on performance, and flow characteristics within the cell. Experimental data show the positive effects of temperature and pressure on performance, which is also analyzed by the two-phase multicomponent flow model validated by test data. The predicted performance curves agree reasonably with the experimental data and demonstrate the increase in cell performance at elevated temperature. In addition, the simulation model proposed in this paper can also reasonably capture the flow characteristics in a PEMFC. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.