NOVELTY - A porous surface on a nickel substrate is provided by treating the substrate with a flowing stream of gas comprising ammonia or hydrazine at greater than or equal to 4OO (preferably 660) degrees C to provide a porous surface comprising pores having access to the surface.    USE - The method is used for providing a porous surface on a nickel substrate, e.g. nickel surface coating, or supported or unsupported sphere, powder, wire, foil, sheet, mesh, rod, tube, shape memory article, single crystal or foam, for a nickel catalyst, e.g. Raney nickel catalyst (claimed) for steam reforming of hydrocarbons, dry reforming of biogas, hydrogenation of sugars, activation of fuel in high temperature fuel cell devices, or catalytic hydrogenation of fatty acids in oils and fats. It can also be used to increase surface area of nickel powders in NiCad battery plates or in nickel-hydride batteries; to provide a cost-efficient way of producing hydrogen fuel cells; to produce porous nickel foils; to make inter alias batteries, fuel cells, capacitors and sensors for used in photonic crystal and optical applications; to make porous shape memory articles made from, e.g. national; or to make fuel cells to replace batteries in wireless applications, e.g. laptop computers or cellphones, or in oil refinery catalysts.    ADVANTAGE - The method utilizes a gas stream having less than 30% water, and the prepared nickel substrates has cracks along the grain boundaries allowing the pores in an interconnected network to have access to the surface making the resultant surface resembles an open sponge.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a nickel substrate having a surface porous layer of 30 (preferably 10) mu m thick and pores having less than 10 (preferably less than 1) mu m diameter;    (2) a method of steam reforming of hydrocarbons, dry reforming of biogas, hydrogenation of sugars, steam reforming, methanation, activation of fuel in high temperature fuel cell devices or catalytically hydrogenating fatty acids in fats and oils comprising using the nickel catalyst;    (3) a method of increasing an area of metal-solid-gas interface in fuel cell membranes comprising using the nickel substrate;    (4) a method of increasing surface area of a nickel powder, e.g. in a nickel-cadmium battery plate or a nickel-hydride battery, comprising providing a porous surface as the nickel powder;    (5) a method of making a porous substrate, e.g. filter, comprising taking a coarse porous substrate, plating nickel on a substrate, and providing a porous surface on the nickel; and    (6) a method of refreshing a nickel catalyst comprising treating it continuously during operation by adding 0.1% ammonia or hydrazine to process gas.