The crossover effect of the land/channel width ratio of bipolar plates in polymer electrolyte membrane fuel cells is experimentally investigated in this study. To isolate the effect of the land/channel width ratio, three different types of bipolar plates of a fixed sum and channel width are specially prepared. With three different bipolar plates, measurements are taken of electrochemical performance, inlet pressure, and hydrogen crossover rate. When the stoichiometric ratio of hydrogen is 1.5, the standard type of bipolar plate, BP2 (land width = 0.75 mm, channel width = 1.05 mm) show the best performance. However, according to increasing stoichiometric ratio of hydrogen, BP3 (land width = 1.12 mm, channel width = 0.68 mm) has the best performance, especially at the medium and high current range. For the crossover rate, the biggest amount of hydrogen gas crossover to the cathode in BP3. This is because of the anode inlet pressure caused by the largest land/channel ratio of BP3. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.