In this research, a novel procedure for membrane electrode assembly (MEA) preconditioning was introduced based on proton exchange membrane fuel cell (PEMFC) steaming. Cell steaming was carried out by injection of steam simultaneously to the anode and cathode sides of PEMFC for 2.5 h. It was found that cell steaming enhances MEA performance compared to identical Un-steamed-MEAs which were conditioned by the different conventional methods: constant voltage at 0.6 V (same as Steamed-MEA), and cell voltage cycling; 963 mW cm(-2) vs. 703 mW cm(-2) and 645 mW cm(-2), respectively. Electrochemical impedance spectroscopy (EIS) results demonstrated that cell steaming is an effective procedure for decreasing of ohmic resistance and charge and mass transfer limitations. The mass transfer resistance decreased when the cell steaming was done in the MEA; 0.0055 Omega cm(2) for Steamed-MEA vs. 0.0368 Omega cm(2) and 0.0291 Omega cm(2) for Un-steamed-MEA-1 and Un-steamed-MEA-2, respectively. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.