Abstract: In an electrolytic cell for the production of chlorine and hydrogen from hydrochloric acid, the cell comprising a plurality of spaced bipolar electrodes each provided with vertical grooves for the passage of gas, and a plurality of diaphragms each subdividing the space between adjacent electrodes, the improvement which comprises providing the grooves with a depth of about 18 to 35 mm at least in the upper part of the electrodes. Advantageously the grooves have a width of about 2 to 3 mm and the spacing between adjacent grooves of each electrode is about 4 to 6 mm, the depth of the grooves at their bottoms is about 12 to 15 mm and increases in upward direction to about 20 to 30 mm, and the distance between the electrodes and the diaphragms is from about 0.05 to 1 mm. The voltage drop and energy consumption are less than with different groove configurations and the chlorine content of the hydrogen gas is reduced.