Water transport through the membrane of a polymer electrolyte fuel cell (PEFC) was investigated by not only measuring the voltage variation but also visualizing the accumulation of water at the anode for various values of operating parameters, such as the humidity, current density, stoichiometry, location of humidification, and membrane properties. The PEFC was operated in the dead-end mode to prevent the discharge of water from the anode. The water transport in the PEFC was characterized by the elapsed time for the voltage to reach its limit. Anode visualization showed water transport under various conditions. In addition, the mass balance of water at the anode of the PEFC was considered. The variations of water diffusion and electro-osmotic drag were analyzed based on the experimental results. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.