Low humidification, large air stoichiometry, dry hydrogen and low operational temperature makes open-cathode proton exchange membrane fuel cells (PEMFCs) with forced-air convection, which is designed for portable applications, quite different from that used in automobile vehicles. In this paper, PEMFCs humidified at 30 degrees C using Nafion 212 and Nafion 211 as electrolytes were systematically investigated under simulating conditions. These conditions included air stoichiometry from 3 to 100 and cell temperature from 30 degrees C to 60 degrees C. The results indicate that the thinner membrane (Nafion 211) had better performance and more stable voltage output under air dual-function configuration than Nafion 212. Furthermore, the dynamic response of the voltage with cell temperature was also studied during rising and cooling procedure between 30 degrees C and 60 degrees C. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.