NOVELTY - A gas diffusion layer (12, 14) that is positionable between an electrode and a flow field in a proton exchange membrane (PEM) fuel cell (10), comprises a fiber and non-fiber material in a ratio such that the water vapor diffusion transport resistance is greater than 0.8 s/cm measured at 80 degrees C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness of less than or equal to 300 microns, or the water vapor diffusion transport resistance is lower than 0.4 s/cm measured at 80 degrees C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness of greater than or equal to 100 microns.    USE - As gas diffusion layer in fuel cell (claimed) are used as an electrical power source e.g. in automobiles to replace internal combustion engines.    ADVANTAGE - The binder resin increases the tortuosity for gas moving through the diffusion layer, where the tortuosity is 1.5-20.    DETAILED DESCRIPTION - A gas diffusion layer (12, 14) that is positionable between an electrode and a flow field in a proton exchange membrane (PEM) fuel cell (10), comprises a fiber and non-fiber material in a ratio such that the water vapor diffusion transport resistance is greater than 0.8 s/cm measured at 80 degrees C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness of less than or equal to 300 microns, or the water vapor diffusion transport resistance is lower than 0.4 s/cm measured at 80 degrees C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness of greater than or equal to 100 microns. The diffusion layer further comprises a microporous layer on at least one side of the first resin-containing layer. An INDEPENDENT CLAIM is included for fuel cell comprising an anode gas flow field (16) having channels (60) for introducing a first gas to the fuel cell, an anode diffusion layer disposed over the anode gas flow field; an anode catalyst layer disposed over the anode diffusion layer; a polymeric ion conductive membrane (62) disposed over the anode catalyst layer; a cathode catalyst layer disposed over the polymeric ion conductive membrane; a cathode diffusion layer disposed over the cathode catalyst layer; a cathode gas flow field (20) having cathode plate channels for introducing a second gas to the fuel cell, the cathode flow field being disposed over the cathode diffusion layer, where at least one of the anode diffusion layer or the cathode diffusion layer comprises the gas diffusion layer.    DESCRIPTION OF DRAWING(S) - The figure shows a perspective view of a fuel cell incorporating the diffusion layer.    Proton exchange membrane fuel cell (10)    Gas diffusion layers (12, 14)    Anode flow field (16)    Anode (18)    Cathode flow field (20)    Cathode (22)    Channels (60)    Polymeric ion conductive membrane (62)