Cold starting performance and high temperature operation are current issues in the development of high performance polymer electrolyte fuel cell (PEFC) electrodes. Although excess water must be removed to improve these aspects of electrode performance, it is also important to adopt a structure that prevents the electrodes from drying up. In the face of this conflicting relationship, it is therefore difficult to design an electrode structure with the required properties. For this reason, using technology jointly developed with Kyoto University and Toyota R&D Labs., Inc., the relationship between structural factors and performance was identified by applying a two-phase flow simulation to the complex microstructure of the gas diffusion layer (GDL) to optimize the electrode structure. As a result, an electrode structure was designed that improves high temperature operation while maintaining cold starting performance. The simulation results were then validated by experiments.Copyright © 2010 by ASME