NOVELTY - A gas diffusion layer for fuel cell, has a flexible, electrically non-conductive, porous material with a solid matrix, interconnected pores or interstices through the solid matrix, at least one external surface and internal surfaces. A portion of the external surface is coated with layer(s) of an electrically conductive material comprising a mixture of at least two populations of electrically conductive carbon particles.    USE - For a fuel cell (claimed).    ADVANTAGE - The inventive gas diffusion layer can maintain effective gas diffusion and maintain effective current conductivity without adversely impacting fuel cell performance or adding significant thickness, weight or expense.    DETAILED DESCRIPTION - A gas diffusion layer for a fuel cell, comprises a flexible, electrically non-conductive, porous material having a solid matrix, interconnected pores or interstices through the solid matrix, at least one external surface and internal surfaces. The internal surfaces are the surfaces of the walls of the pores or interstices. A portion of the external surface is coated with layer(s) of an electrically conductive material. The electrically conductive material comprises a mixture of at least two populations of electrically conductive carbon particles. The carbon particles are uniformly mixed in the direction of a plane extending along the external surface. The two populations are:    (1) at least population A of electrically conductive non-fibrous carbon particles and population B of electrically conductive non-fibrous carbon particles, where the ratio of the D50% of population A and the D50% of population B is 1:m, with m being greater than or equal to500, preferably greater than or equal to2000;    (2) at least population C of electrically conductive non-fibrous carbon particles and population D of electrically conductive carbon fibers, where the ratio of the D50% of population C and the average length of the fibers of population D is 1:n, with n being greater than or equal to2, preferably greater than or equal to10; and    (3) at least population E of electrically conductive carbon fibers and population F of electrically conductive carbon fibers, where the ratio of the average length of the fibers of population E and the average length of the fibers of population F is 1:p, with p being greater than or equal to2, preferably greater than or equal to10.    INDEPENDENT CLAIMS are also included for:    (A) a device comprising the above specified gas diffusion layer and a layer of catalyst for a fuel cell (10);    (B) a fuel cell comprising the layers of a first separator or bipolar plate, a first gas diffusion layer (13), an anode (15) comprising a layer of particulate catalyst, a solid polymer electrolyte or proton exchange membrane, a cathode (15A) comprising a layer of particulate catalyst, a second gas diffusion layer (13A), and a second separator or bipolar plate;    (C) a gas diffusion electrode for a fuel cell, comprising a catalyst on an external surface of a solid substrate; and    (D) a bipolar plate (12, 12A) for a fuel cell, comprising a flexible, electrically non-conductive, non-permeable material having a solid matrix and external surface(s).    The catalyst comprises noble metal(s). The external surface of the porous material coated with the electrically conductive material is in contact with the layer of catalyst.    DESCRIPTION OF DRAWING(S) - The figure is a schematic view in side elevation of a fuel cell having two compressible coated foam gas diffusion layers of the invention between the membrane electrode assembly and the bipolar plate.    Fuel cell (10)    Bipolar plate (12, 12A)    Gas diffusion layers (13, 13A)    Anode (15)    Cathode (15A)