Water management in a PEM fuel cell significantly affects the fuel cell performance and durability. The gas diffusion layer (GDL) of a PEM fuel cell plays a critical role in the water management process. in this short communication, we report a simple method to measure the water transport rate across the GDL Water rejection rates across a GDL at different cathode air-flow rates were measured. Based on the measurement results, the fuel cell operating conditions, such as current density, temperature, air stoichiometry and relative humidity, corresponding to membrane drying and flooding conditions were identified for the particular GDL used. This method can help researchers develop GDLs for a particular fuel cell design with specific operating conditions and optimize the operation conditions for the given PEM fuel cell components. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.