According to the H-2 and fuel cell road map in Japan, the target operating temperature of polymer electrolyte fuel cell (PEFC) should be 90 degrees C from 2020 to 2025. In this study, the impact of polymer electrolyte membrane (PEM) and gas diffusion layer (GDL)'s thickness on heat and mass transfer characteristics as well as power generation performance of PEFC is investigated at operating temperature of 90 degrees C. The in-plane temperature distributions on anode and cathode separator are also measured using thermograph. As a result, it is observed that the increase in power from 1 W to 5 W at the current density of 0.80 A/cm(2) as well as even temperature distribution within 1 degrees C can be obtained at operating temperature of 90 degrees C by decrease in GDL's thickness from 190 mu m to 110 mu m. In addition, the power is increased from 3 W to 4 W at the current density of 0.80 A/cm(2) operated at 90 degrees C by decrease in the PEM's thickness from 127 mu m to 25 mu m. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.