NOVELTY - The electrolyzer comprises a housing with electrodes (2, 3) that are connected to the poles of a direct current supply source and are separated from each other by a diaphragm (4), where an electrolytic half cell (5, 6) is defined by the diaphragm, a gas separation chamber that is arranged above the electrolytic cell for the separation of oxygen or the hydrogen from the electrolysis liquid mixed with a gas-liquid mixture, and a further chamber with a demister formed at a top of the gas separation chamber by partitions and the walls of the housing for additional purification of water or oxygen.    USE - The electrolyzer is useful for generating hydrogen and oxygen by electrochemical decomposition of water, where the hydrogen is useful in smaller tanks in motor cars for enabling electric drive of a motor vehicle.    ADVANTAGE - The economic electrolyzer is capable of efficiently generating hydrogen and oxygen with high purity in a simple manner with high safety.    DETAILED DESCRIPTION - The electrolyzer comprises a housing with electrodes (2, 3) that are connected to the poles of a direct current supply source and are separated from each other by a diaphragm (4), where an electrolytic half cell (5, 6) is defined by the diaphragm, a gas separation chamber that is arranged above the electrolytic cell for the separation of oxygen or the hydrogen from the electrolysis liquid mixed with a gas-liquid mixture, and a further chamber with a demister formed at a top of the gas separation chamber by partitions and the walls of the housing for additional purification of water or oxygen. The gas separation chambers and further chambers are arranged in a vertical arrangement by horizontal partition walls comprising passage openings for the gas liquid mixture and for dripping off liquid. The partition walls are assembled in the horizontal direction of gas flow and connected with the housing wall in a water-tight manner to form a unit. Outlets for the purified hydrogen gas and oxygen are provided in a topside of a lid (17), and feed openings and outlets for the water and the electrolysis liquid are provided in a bottom wall of electrolysis cells. In the separation chambers, a pipe line that opens into the waters/electrolysis liquid in the electrolysis chamber or a breakdown for the recycle of the dripping off liquid is provided. A second chamber comprising a further demister and/or a material with catalytic effect is arranged within the housing for supplementary purification of the vertically flowing water or oxygen to form a unit. The vertically arranged chambers are hermetically enclosed by a sleeve-shaped pressure body having a bottom wall (20) and a top wall. The diaphragm withstands at a height so that a defined distance is given between the upper partition of the electrolysis chambers and the electrode, and the electrolysis chambers are separated via the diaphragm walls. The demister comprises nickel fibers or nickel wires or other catalyst support such as ceramic fibers or porous ceramic body applied with catalysts in the chambers. A perforated plate having openings is applied on one side of an anode and/or a cathode of the electrode, where a locking slider with hole arrangements is movable relative to the perforated plate. An insulation layer and/or a surface heating element is applied on the electrode, where through holes are brought into the insulation layer and/or into the surface heating element. The electrodes and the housing are approximately formed. The housing is oval or angular shaped, and the electrodes are plate shaped. A filter arrangement with a membrane is provided into the passage openings for the gas liquid mixture, where the membrane allows gaseous oxygen or hydrogen produced by electrolysis to pass and partly restrains the carried liquid mixture. Electrolyzers are combined to form a unit, and outputs and a supply line or a gas discharge line are connected.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an electrolyzer.    Electrodes (2, 3)    Diaphragm (4)    Electrolytic half cells (5, 6)    Lid (17)    Bottom wall. (20)