The invention relates to chemical engineering, in particular to devices for electrolyzing aqueous solutions of alkali or alkali-earth metal chlorides and for obtaining gaseous electrolytic products such as chlorine and oxygen. It can be used for water purifying and disinfecting processes and for electrochemically producing some chemical products. The inventive device includes at least one electrochemical reactor (1) comprising from 2 to 16 electrochemical cells. Lines for supplying and discharging cathode and anode chambers are embodied in the form of pipelines having an inner diameter equal to or less than 0.5 of the interelectrode distance and lengths which are equal to or greater than 2 Ld, wherein the interelectrode distance is an anode-to-cathode distance and Ld is the cathode length. A manifold for supplying an initial solution (10), a lower manifold of the cathode circulation circuit (15), a heat exchanger (18), an upper manifold of the cathode circulation circuit (14) and a manifold for collecting gaseous products of the anodic chamber cells (13) are arranged along the same vertical axis. The upper manifold of the cathode circulating circuit (14) is mounted at a height not less than then the distance equal to Ld from the cathode chamber output. The number of the inputs and outputs of the manifolds corresponds to the number of cells in the reactor, and said inputs and outputs are arranged symmetrically with respect to the vertical axis of symmetry of the manifold.