Water treatment with electrolysis was performed in a specially made electrolytic cell consisting of TinO2n-1 containing ceramic anode and stainless still cathode. The total electrolysis cell resistance decreases if the current density applied to the electrolysis cell is increased. During electrolysis at constant current strength, the amount of chlorine which is delivered in the process of electrolysis is not dependent on the electrode surface. By varying the velocity of water flow, as well as current intensity, it is possible to achieve the formation of desired amount of chlorine in electrolysis process. The specific electric work for formation of chlorine decreases with increase of electrode area at constant current strength and increase at a constant current density.