Fuel cells represent a clean alternative to current technologies for utilizing hydrocarbon fuel resources. Polymer electrolyte membrane fuel cells (PEMFCs) have acquired due importance as they are best suited for applications where a quick start up is required such as in automobiles. The prime requirements of fuel cell membranes are high proton conductivity, low methanol/water permeability, good mechanical and thermal stability and moderate price. Membranes and the operating parameters together have a profound influence on performance of PEMFCs. Perfluorinated ionomers, hydrocarbon and aromatic polymers and acid-base complexes have been described in the review. The performance of this special class of polymers, considering their structure-property relationship and the current research involving their applicability in fuel cell systems are presented. Modifications made to Nafion((R)) membranes, the conceptual design of substitutes for perfluorosulfonic acid materials and modifications made to aromatic membranes to render them suitable for this application have been summarized. Promising avenues for further research in this area have been identified. (c) 2005 Published by Elsevier B.V.