NOVELTY - Oxygen and carbonaceous fuel are supplied combusted to form exhaust gas having steam and carbon dioxide. Portion(s) of energy of exhaust gas is converted into electric energy, and exhaust gas is separated into water fraction (6) and gaseous fraction containing carbon dioxide (5). Water fraction is fed to electrolysis reactor (2) by passing 0-100% of condensed water, and remaining water fraction from external water source. Produced electric energy (11) is passed to electrolysis reactor for decomposing water. Thus, hydrogen and/or electric energy is produced.    USE - Production of hydrogen and/or electric energy.    ADVANTAGE - Hydrogen and/or electric energy is efficiently produced without emitting carbon dioxide.    DETAILED DESCRIPTION - Pure oxygen and a carbonaceous fuel are supplied in a stochiometric ratio to a combustor (1), and combusted to form an energy rich exhaust gas comprising steam and carbon dioxide at high temperature and pressure. Portion(s) of energy of the exhaust gas exiting the combustor is converted into electric energy, and exhaust gas is separated into pure water fraction (6) and a gaseous fraction containing carbon dioxide (5) by condensing the water fraction. The gaseous fraction is converted to unit for storing or sequestering carbon dioxide. Water fraction is fed to an electrolysis reactor (2) by passing 0-100% of the condensed water, and the remaining water fraction from an external water source. The produced electric energy (11) (0-100%) is passed to electrolysis reactor for decomposing water to hydrogen gas and oxygen gas by electrolysis. The remaining fraction of energy is fed to a net grid, and oxygen gas in electrolysis reactor is fed to the combustor. Thus, hydrogen and/or electric energy is produced. An INDEPENDENT CLAIM is included for plant for combined production of hydrogen and/or electric energy.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram explaining production of hydrogen and/or electrical energy.    Combustor (1)    Electrolysis reactor (2)    Carbon dioxide-containing gaseous fraction (5)    Water fraction (6)    Electrical energy (11)