NOVELTY - Fabrication of a bipolar plate comprises providing a flowfield skeleton (30), which comprises a sacrificial core (32) overplated by a hydrogen permeation barrier layer; molding an electrically conductive polymeric composite material (40) about the flowfield skeleton to define opposite sides of the bipolar plate; and curing the molded polymeric composite material, such that the hydrogen permeation barrier layer adheres to the composite material and the sacrificial core melts away from the composite material and the barrier layer to define a flowfield cavity.    USE - The process is for fabrication of a bipolar plate for fuel cell stack configured as a stand-alone source of electrical power for vehicle (claimed) e.g. automobiles (i.e. passenger automobile, car, light- or heavy-duty truck, or tractor trailer), farm equipment, aircraft, watercraft, and railroad engines.    DETAILED DESCRIPTION - Fabrication of a bipolar plate comprising a flowfield defined between opposite, electrically conductive sides of the bipolar plate, comprises:    (A) providing a flowfield skeleton, which comprises a sacrificial core overplated by a hydrogen permeation barrier layer;    (B) molding an electrically conductive polymeric composite material about the flowfield skeleton to define the opposite sides of the bipolar plate;    (C) curing the molded polymeric composite material such that the hydrogen permeation barrier layer adheres to the composite material, and the sacrificial core melts away from the composite material and the barrier layer to define a flowfield cavity between the opposite sides of the bipolar plate; and    (D) removing the melted sacrificial core from the flowfield cavity.    An INDEPENDENT CLAIM is also included for a fuel cell stack comprising a bi-polar plate including a polymeric composite flowfield portion and a non-conductive fluid header portion (15) coupled to the flowfield portion, where flowfield portion is of unitary construction and defines opposite, electrically conductive sides and a flowfield between the opposite, electrically conductive sides; the opposite, electrically conductive sides of the flowfield portion define an interior face exposed to the flowfield; the interior face of the flowfield portion is overplated, at least in part, by a hydrogen permeation barrier layer; and the flowfield portion bounds a portion(s) of the non-conductive fluid header portion, such that the header is held by the flowfield portion.    DESCRIPTION OF DRAWING(S) - The figure is an illustration of a process for fabricating a bipolar plate.    Fluid header portion (15)    Flowfield skeleton (30)    Sacrificial core (32)    Upper and lower molds (34, 36)    Electrically conductive polymeric composite material (40)