A process and a device are provided for producing hydrogen gas from water and carbon. The process includes introducing steam and powdered carbon in stoichiometric ratio of carbon to water into a preheated oxidization chamber in such a way that a gas plasma is produced in which the steam is decomposed into its hydrogen and oxygen gas components and oxygen is combined with carbon to form carbon dioxide gas in an exothermic reaction at temperatures above 2000.degree. C., and separating the carbon dioxide gas from the hydrogen gas. The device for conducting this process has an oxidization chamber defined in a hollow body and being provided with a preheater and having at least one inlet port for introducing steam into the oxidization chamber, at least one inlet port for introducing powdered carbon into the oxidization chamber, and at least one exit port for carrying off generated hydrogen gas and/or generated carbon dioxide gas from the oxidization chamber.