H3PO4 content plays a critical role in high temperature proton exchange membrane fuel cells (HT-PEMFC), as it is responsible for the majority of the conductivity of the key components under high temperature operation. The conductivities of commercial AB-PBI membranes doped by immersing in 85 wt.% H3PO4 for different times and temperatures are investigated. The effect of H3PO4 loading in electrodes, including the AB-PBI polymer and a Pt/C catalyst, is also studied. The as-prepared electrodes and membranes are combined to fabricate a membrane electrode assembly for HT-PEMFCs. The results reveal that AB-PBI membranes doped with 85 wt.% H3PO4 at 90 degrees C for 9 h display a maximum conductivity of 33 mS cm(-1). This membrane was selected and combined with electrodes including 15 wt.% AB-PBI and 0.75 mg cm(-2) Pt with different H3PO4 loadings. A maximum current density of 260 mA cm(-2) was achieved in the as-prepared MEA (with 5 mg cm(-2) H3PO4 in electrodes) operating at 0.6 V and 160 degrees C, using oxygen and hydrogen. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.