A water management technique has been developed for solid polymer electrolyte fuel cells which demonstrates both performance and diagnostic benefits. Through this technique a substantial proportion of the water in the cathode can be removed via the anode fuel stream. This is accomplished by imparting a water concentration gradient through the polymer membrane, thereby increasing the back diffusion rate of water. A reduction in cathode overpotential is observed without noticeable increase in membrane resistance. The technique can be used to remove mass transport limitations at both high current densities and low oxidant stoichiometries.