The electrolysis apparatus for the manufacture of chlorine from aqueous alkali metal halide solutions has at least one electrolysis cell the electrodes of which, separated by a separating wall, are arranged in a housing of two hemispherical shells. The housing is furthermore provided with equipment for the feed of the starting materials for electrolysis, and equipment for the discharge of the electrolysis products. The separating wall is clamped by means of sealing elements between the rims of the hemispherical shells and positioned between power transmission elements of non-conductive material. The electrodes are fastened via spacers to the shells and connected mechanically and electrically with the shells via the rims thereof. The hemispherical shells of adjacent cells are positioned flatwise one upon the other, and the end positioned shells of the electrolysis apparatus are supported by pressure compensation elements.