The method of electrochemical concentration of solutions involves feeding a weak solution of sodium chloride with a constant temperature of 20 ± 0.5 °C at pH 6.5 ± 0.3 into the chambers of the electrolyzer, where ion exchange membranes with a working surface of 0.2 dm2 each are installed, with the production of alkali in one chamber and a concentrated solution of sodium chloride in the other. A three-chamber electrolyzer is used; sodium chloride solution is fed into all its chambers; to suppress the formation of active chlorine in the anode chamber, alkali is dissolved in it until the alkalinity reaches more than 500 mg-eq/dm3; sodium chloride solution is removed from the anode and cathode chambers after reaching a concentration of more than 100 g/dm3 in the solution