Proton exchange membrane fuel cells operating with Nafion (R) membranes have encountered numerous problems associated with water management and CO poisoning because of their low temperature of operation. Higher temperature membranes have been investigated, one such membrane being polybenzimidazole (PBI). This paper presents a parametric model, which predicts the polarization performance of an intermediate temperature proton exchange membrane fuel cell (PEMFC). It also investigates the effects of porous media characteristics on fuel cell performance. Results show that for intermediate temperature fuel cells, mass limitation effects are absent as long as the catalyst regions are sufficiently permeable. It is predicted that the greatest scope for improving PBI PEMFC performance is increasing the membrane conductivity and improving the catalyst performance, as it interfaces with the PBI membrane. (c) 2005 Published by Elsevier B.V.