Liquid water transport is one of the key challenges for water management in a proton exchange membrane (PEM) fuel cell. Investigation of the air-water flow patterns inside fuel cell gas flow channels with gas diffusion layer (GDL) would provide valuable information that could be used in fuel cell design and optimization. This paper presents numerical investigations of air-water flow across an innovative GDL with catalyst layer and serpentine channel on PEM fuel cell cathode by use of a commercial Computational Fluid Dynamics (CFD) software package FLUENT. Different static contact angles (hydrophilic or hydrophobic) were applied to the electrode (GDL and catalyst layer). The results showed that different wettabilities of cathode electrode could affect liquid water flow patterns significantly, thus influencing on the performance of PEM fuel cells. The detailed flow patterns of liquid water were shown, several gas flow problems were observed, and some useful suggestions were given through investigating the flow patterns. (c) 2007 Elsevier B.V All rights reserved.