Abstract: An electrolytic cell comprises a housing (12), means (21) defining a liquid level (25) in said housing (12), a first contact surface (32) positioned above said liquid level (25) for making contact with a removable electrode (20) when positioned in said housing (12). A second contact surface (36) is positioned above said liquid level (25) and electrically isolated from said first contact surface (32) for making contact with said removable electrode (20) when positioned in said housing (12). A method of electrolysis in such a cell comprises supplying electrical power to said electrode (20) at an electrolysing potential (U.sub.P) and controlling the electrolysing potential (U.sub.P) in response to the potential (U.sub.2) sensed at the second contact surface (36). Control of the electrolysis process is possible without influence of any unknown and variable resistance between the first contact surface and the electrode.