Abstract: Device for the conversion of chemical energy of hydrocarbons into electric energy by plate-shaped high-temperature fuel cells, arranged like a stack around a central reaction space, on the basis of zirconium oxide as solid electrolyte, wherein gas jet pumps are provided for the transport and mixing of a part of the O.sub.2 excess and ballast gas with the gaseous oxygen carrier, as well as for the transport and mixing of a part of the fuel excess and the reaction products with the gaseous fuel, and a central perforated feed pipe and a perforated body with catalyst coating are provided such that endothermic conversion reactions are performed within the central reaction space.