An electrolysis device producing alkali metals from a liquid alkali metal heavy metal alloy, including at least two connected tubes forming an electrolysis unit. Two solid electrolyte tubes are arranged concentrically in each tube and oriented with openings towards one end of each tube such that a first annular gap for guiding a liquid alkali metal forming an anode is located between the inside of the tube and the outside of the solid electrolyte tubes. An alloy inlet and outlet for the liquid alkali metal in each of the tubes leads into the first annular gap of a tube. An inner chamber sealed off from the alloy inlet, first annular gap, and alloy outlet in each solid electrolyte tube receives liquid alkali metal that can be used as a cathode connected to the alkali metal outlet. Two respective closure devices are arranged at the two ends of each tube.