NOVELTY - Proton exchange membrane fuel cell assembly comprises seal assembly including first seal parts and one second seal part. The first seal parts are applied to uneven surfaces of component elements. Each first seal part has smooth surface that is coplanar with sealing surfaces of end plates. The second seal part comprises elastomer with low compression set and low compression modulus.    USE - For fuel cell power plant.    ADVANTAGE - The inventive fuel cell assembly includes a manifold seal system, which is very compressible and has a low creep. The manifold seal system is stable in the presence of hydrogen, oxygen and water. An effective seal is provided to the fuel cell for all pressure differentials experienced by the seal during fuel cell operation, without leaking, and does not require periodic tightening of manifold to maintain the seal over time. The sealing system allows easy removal of the manifold.    DETAILED DESCRIPTION - A proton exchange membrane fuel cell assembly has fuel cell component elements (8) extending under compressive pressure between a pair of end plates (9), and a reactant gas manifold (10). The elements have mutually uneven surfaces at their ends.    The fuel cell assembly comprises a seal system (13), which includes first seal parts and one second seal part. The first seal parts are applied to uneven surfaces and extend from one end plate to the other end plate at corresponding regions of the uneven surfaces. Each first seal part has a smooth surface that is facing the manifold and is coplanar with sealing surfaces of the end plates. The first seal parts comprise silicone rubber. The second seal part comprises an elastomer (15) disposed adjacent the entire contact perimeter surface (16) of the manifold. The elastomer has a low compression set and low compression modulus.    An INDEPENDENT CLAIM is also included for a method of sealing a perimeter surface of a reactant gas manifold to end plates and fuel cell component elements of proton exchange membrane fuel cell. The method comprises applying type(s) of silicon rubber to the regions of fuel cell elements that are to be sealed to the manifold, to provide bridges (14) having smooth and flat surfaces, where the manifold is to be sealed. The silicon rubber is caused to cure, and an elastomer having low compression set and low compression modulus is provided. The manifold is installed on the fuel cell with its entire contact perimeter surface in contact with the elastomer. The elastomer is between the manifold and the bridges and end plates.    DESCRIPTION OF DRAWING(S) - The drawing shows a partial front elevational view of the inventive fuel cell having the seal.    Fuel cell component elements (8)    End plates (9)    Reactant gas manifold (10)    Seal system (13)    Bridges (14)    Elastomer (15)    Perimeter surface of manifold (16)