Bipolar plates (BPs) are a key component of proton exchange membrane (PEM) fuel cells with multifunctional character. They uniformly distribute fuel gas and air, conduct electrical current from cell to cell, remove heat from the active area, and prevent leakage of gases and coolant. BPs also significantly contribute to the volume, weight and cost of PEM fuel cell stacks. Hence, there are vigorous efforts worldwide to find suitable materials for BPs. The materials include non-porous graphite, coated metallic sheets, polymer composites, etc. This paper reviews various types of materials, in use and proposed, for BPs and critically examines their physical and chemical properties. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.