A closed-cycle multi-step thermochemical process is described for the production of hydrogen and oxygen from water. The disclosed process utilizes auxiliary compounds of the system iron-chlorine. By using the following two basic process steps:A. reacting an iron oxide with hydrogen chloride or a mixture of hydrogen chloride and chlorine to form iron (II) chloride or iron (III) chloride andB. reacting iron or iron (II) oxide with water to form iron (II) oxide or iron (II) (III) oxideIt is possible to employ a variety of additional steps so that the sum total of the reaction steps consume water, produce hydrogen and oxygen and regenerate the desired starting materials within the closed system.