Abstract: Disclosed is an improved process for electrolytically producing alkaline chlorate, carried out at an increased temperature by using an apparatus of a column type. The apparatus has a lower electrolysis zone, an intermediate reaction zone and an upper hydrogen-separation zone. The reaction zone has a central hollow section and a circumferential hollow section surrounding the central section. A solution to be electrolyzed is forced to circulate through the three zones by hydrogen gas generated so that the solution is allowed to flow down through the circumferential hollow section in a piston-flow manner after the hydrogen gas is separated from the solution. While the solution is passing through the circumferential section, effective auto-oxidation of hypochlorous acid is attained thereby causing the current efficiency of the electrolysis to be improved.