TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: (I) further comprises an other catalyst coating, where the other catalyst coating is applied directly to the other one of the two sides. (I) has: a catalyst loading of 0.01-0.15 (preferably 0.02-0.08) mg/cm2, where the one of the two sides is an anode side; or catalyst loading of 0.1-0.35 (preferably 0.15-0.25) mg/cm2, where the one of the two sides is a cathode side. Preferred Components: The proton exchange membrane is hydrocarbon-based or non-fluorinated (preferred). The catalyst coating has: a thickness of less than 200 (preferably 100) nm; and only active catalytic species, preferably platinum. The openings are: defined in a regular array across the catalyst coating; irregularly scattered across the catalyst coating; or elongated, non-straight, and of varying widths and lengths, and are irregularly scattered on the catalyst-receiving surface, and the catalyst coating forms an irregular agglomerational structure on the proton exchange membrane. The openings has 1-15 nm in width on average. The irregular agglomerational structure has semi-contiguous agglomerations having 5-40 nm on average. The catalyst coating has an electrochemical catalyst surface area of 10-80 (preferably 20-60) m2/g. The catalyst coating is electrically conductive. Preferred Method: The method further comprises inducing the roughness in the catalyst-receiving surface of the proton exchange membrane prior to the step of applying. The method comprises applying a deliberately discontinuous layer of the catalyst coating directly onto the one of the two opposite sides of the proton exchange membrane in a manner that many scattered openings providing passages to the proton exchange membrane are defined through the applied catalyst coating, with electro-chemical active surfaces of the catalyst coating exposed in the openings. The catalyst coating applied in the step of applying is continuous or discontinuous. The one of the two sides of the proton exchange membrane has a roughness greater than a thickness of the catalyst coating applied to it in the step of applying, and the applied catalyst coating has high points corresponding to the roughness, where the step of defining many openings includes abrading the high points. The step of inducing the roughness in the catalyst-receiving surface includes: depositing fine inorganic particles in a scattered manner on it; and mixing inorganic particles in the material of the proton exchange membrane, and casting the membrane in a manner that some of the inorganic particles migrate to the surface of the membrane, creating the roughened membrane surface. The step of defining the many openings includes: vaporizing catalyst; or swelling the proton exchange membrane, which is fissuring the catalyst layer and defining many openings. The step of vaporizing catalyst is effected using a laser beam. The step of applying the deliberately discontinuous layer of catalyst includes sputter-coating the catalyst. The step of sputter-coating includes sputter-coating at pressure conditions set above predetermined operational parameters. The step of sputter-coating is effected at a pressure of above 0.05 (preferably 0.2) mbar. EXAMPLE - No suitable example given.