Interest currently focuses on proton exchange membrane fuel cells that use a solid ionomer as the electrolyte. The relatively low operating temperature of this electrolyte makes it more suitable for use in a vehicle rather than cells using other higher temperature electrolytes. Advancements are needed in the components of this cell to make it commercially viable, including a better proton exchange membrane and improved porous electrodes. The membrane needs a modification of its properties to increase the migration rate of desirable species such as protons. The electrodes involve the transfer of mass, heat, and electrical charge and must be improved and optimized. Improved catalysts are also needed to increase the reaction rates in these electrodes. Our research activities involve both experimental studies and theoretical modeling of the processes to provide interpretation of the data and ultimate optimization of performance.