Process for producing hydrogen comprising reacting at least one hydrocarbon and steam in the presence of a complex metal oxide and a steam-hydrocarbon reforming catalyst in a production step under reaction conditions sufficient to form hydrogen gas and a spent complex metal oxide, wherein the complex metal oxide is represented by the formula AxByOn wherein A represents at least one metallic element having an oxidation state ranging from +1 to +3, inclusive, wherein the metallic element is capable of forming a metal carbonate; x is a number from 1 to 10, inclusive; B represents at least one metallic element having an oxidation state ranging from +1 to +7, inclusive; y is a number from 1 to 10, inclusive; and n represents a value such that the complex metal oxide is rendered electrically neutral.