Abstract: The end plate assemblies in a fuel cell stack are conductive and made from metal that is susceptible of corroding in the hostile fuel cell environment. Coolant fluid circulates through these plates. Reactants must also be fed through the end plate assemblies plate. The reactant and coolant fluids are delivered through manifolds that communicate with each cell. Savings in weight and improvements in corrosion resistance are achieved by fabricating headers for these pressure plates of polymeric material. Each header has fluid inlet or outlet ports and internal passageways that communicate with passageways in the cell assemblies located between the metal pressure plates.