An apparatus for the superficial electrolytic treatment of metal strips, comprising several separate and non-communicating tanks, or containers, located along the path of metal strip (13). A series of electrodes in pairs (14, 15, 14", 15", 14", 15"), arranged as tunnels, is situated along the path. Each pair is associated with a container (2, 2", 2"), in which an electrod 14, 14", 14") of each pair is located above the strip and the other (15, 15", 15") is located below said strip, in a reciprocally opposits position and at an appropriate distance. The electrode pairs alternately have opposite polarity and each of them is respectively associated with a container. Rollers (3, 3, 3", 3") in pairs for strip pressing are situated at the common border of adjacent containes for the galvanic separation of the strip surface areas facing the electrode pairs of opposite polarity.