NOVELTY - Production of hydrogen from a gaseous hydrocarbon, involves decomposing a hydrocarbon in the presence of a catalyst at high temperature, in the hydrogen generation phase and regenerating the catalyst with steam or with water and eliminating carbon deposited on the catalyst, in the catalyst regeneration phase. The reaction gas (CO+H2) from the catalyst regeneration phase is re-used as a source of energy.    USE - For producing hydrogen for use in fuel cells from gaseous hydrocarbon.    ADVANTAGE - The process provides a high yield and a long life of the catalyst. Since the reaction gas is reused as fuel for maintaining the temperature in the hot chamber energy saving is permitted. The high temperature cracking phase provides an increased amount of hydrogen. The retorts operates alternatively generating hydrogen and regenerating the catalyst, thereby permitting a continuous production of hydrogen.    DETAILED DESCRIPTION - A hydrocarbon is decomposed in the presence of a catalyst into carbon and hydrogen at high temperature, in the hydrogen generation phase. The catalyst is regenerated with steam or with water and the carbon deposited on the catalyst, is eliminated in the catalyst regeneration phase. Carbon monoxide (CO) and hydrogen (H2) are produced as reaction gas. The reaction gas (CO+H2) from the catalyst regeneration phase is re-used as a source of energy. An INDEPENDENT CLAIM is included for the system for the production of hydrogen from the gaseous hydrocarbon. The system comprises a retort (A and/or B), a hot chamber enclosing the retort, a component for supplying the hydrocarbon to the retort and a component for supplying the steam to the retort. The system further comprises a component supplying combustible gas to a burner of the hot chamber and a component for supplying the regeneration gas to an external heat generator and/or to a steam generator and/or to a burner in the hot chamber.    DESCRIPTION OF DRAWING(S) - The figure shows the system for producing hydrogen from a gaseous hydrocarbon.