The performance characteristics of proton exchange membrane fuel cells (PEMPCs) can be affected by a degradation of the membrane-electrode-assembly (MEA). In this paper, the performance degradation of MEA in a single cell PEMFC was examined at 80 degrees C and a backpressure of 10 psi after 100 h of operational time using open circuit voltage (OCV) conditions. A control experiment was conducted by testing the MEA at ambient temperature without backpressure. Both electrochemical impedance spectroscopy (EIS) and an OCV analysis showed that both the conductivity and the performance of the cell operating at 80 degrees C were less than the control values after 100 h of operation. In contrast, an application of 10 psi of backpressure improved the cell conductivity and can maintain OCV in compare with ambient and 80 degrees C conditions. Characterizations of the pre- and post-operation of the MEA (cathode, anode and membrane) by scanning electron microscope-energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD) showed that the MEA performance degradation at 80 degrees C after 100 h resulted mainly from carbon corrosion combined with Pt agglomeration and dissolution, producing a PtS compound with reduced activity at both the cathode and the anode and also drying and cracking of the membrane. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.