The invention concerns a fuel cell comprising an anode chamber, a cathode chamber and a cavity for the electrolytic space, as well as combustion gas supply conduits and carbon dioxide and water discharge conduits for the anode chamber, and, for the cathode chamber, oxygen and carbon dioxide supply conduits and discharge conduits for residual oxygen and residual carbon dioxide. The anode chamber and the cathode chamber receive a metal sponge, the cathode chamber housing a metal or ceramic sponge. Said fuel cell is subdivided into an anode chamber, an outer cathode chamber and a median cathode chamber, separate cavities for electrolytic space located between the anode chamber and the median cathode chamber and the median cathode chamber and the outer cathode chamber. An electrolyte conduit enters the median cathode chamber, the oxygen supply conduits and the oxygen discharge conduits are arranged on the median cathode chamber, and the CO.sub.2 supply conduits and the CO.sub.2 discharge conduits are located on the outer cathode chamber.