Water management in cathode gas diffusion layers and catalyst layers of PEFCs (Polymer Electrolyte Fuel Cells) plays an important role toward the obtainment of optimal performance. Flooding may indeed occur under different operating conditions, in these components, requiring special attention both in the development and in the design processes. Simulation is a reliable tool to support the design of PEFCs, and thus provide designers with a better interpretation of experimental data. Flooding within porous media is still a critical issue for multiphase flow fuel cell modeling, representing a challenge in terms of model reliability. This paper aims at extending the validity of a literature available 1D GDL multiphase model presented in Ref. [24]. Special attention has been devoted to the analysis of the difference between multiphase and non-multiphase (multispecies) approaches, and to the 3D aspects of cell design related to flooding issues. Results indicate that flooding must be treated as a 3D phenomenon, as it has a different impact on the different active area regions. In fact, although the land is the most affected zone, current is mainly limited in the channel zone close to the gas inlet section. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.