New stack for proton exchange membrane fuel cells (PEMFCs) has been developed to improve the performance of PEMFCs under nonhumidifying condition by supplying reactant in series. The electromagnetic pump was used in the circulation pipeline to enhance the flow rate of reactants and thus to reduce the uneven distribution of water. Performance of the new stack was studied by using polarization curves and constant current test under various conditions. (c) 2006 Elsevier Ltd. All rights reserved.