NOVELTY - Hydrogen gas is produced by forming a water-blended hydrocarbon feedstock composition comprising a hydrocarbon feedstock, water, surfactant(s) and water-soluble salt(s); and steam reforming the feedstock to convert the composition to a product comprising hydrogen and carbon oxide(s). The steam is mixed with the feedstock composition to form a vaporized mixture at 50-1200 degrees C.    USE - The hydrogen is used for treating a refinery stream or product by hydrocracking, hydrorefining, hydrotreating or hydrodesulfurizing; and for operating a fuel cell (both claimed). The hydrogen can also be used in chemical processes including ammonia synthesis from nitrogen (by Haber-Bosch process), aromatic hydrogenation, hydroforming olefinic hydrocarbons to convert them to branched-chain paraffins, preparation of alcohols from synthesis gas, and hydrogenation of fats and oils.    ADVANTAGE - Forming a water-blended hydrocarbon feedstock composition prior to steam reforming improves the efficiency of the steam reforming process and the purity of the hydrogen that is produced. The process provides for lower hydrogen cost due to improved efficiency; lower capital cost or increase in throughput for an existing steam reforming unit due to lower water requirements; lower hydrodesulfurization requirement for the hydrocarbon feedstock; lower carbon monoxide and sulfur impurities for a given condition (level of water and of hydrodesulfurization); and more efficient operation and longer equipment life for fuel cell applications e.g. those based on proton exchange membranes. The process allows heavier feedstocks to be handled and transported easily because of their being blended with water.    DETAILED DESCRIPTION - Production of hydrogen gas involves:    (i) forming a water-blended hydrocarbon feedstock composition comprising a hydrocarbon feedstock, water, at least one surfactant and at least one water-soluble salt; and    (ii) steam reforming the water blended hydrocarbon feedstock to convert the composition to a product comprising hydrogen and at least one carbon oxide,    The steam is mixed with the feedstock composition to form a vaporized mixture. The temperature of the vaporized mixture is 50-1200 degrees C. The water-blended hydrocarbon feedstock composition is a water-in-oil emulsion, an oil-in-water emulsion or a micro-emulsion. The surfactant comprises:    (a) a product made from the reaction of an acylating agent with ammonia, an amine, an alcohol or a mixture of at least two of these compounds;    (b) a product comprising (i) a polycarboxylic acylating agent and (ii) a copolymer derived from olefin monomer(s) and alpha,beta-unsaturated carboxylic acid(s) or their derivative linking group derived from a compound having at least two prim. amino groups, at least two sec. amino groups, at least one prim. amino group and at least one sec. amino group, at least two hydroxyl groups, or at least one prim. or sec. amino group and at least one hydroxyl group;    (c) an aromatic Mannich compound derived from a hydroxy aromatic compound, an aldehyde or a ketone, and an amine containing at least one prim. or sec. amino group;    (d) an ionic or a nonionic compound having a hydrophilic-lipophilic balance of 1-40; or    (e) a mixture of at least two of these four components.