Abstract: The present invention relates to a method for treating a surface of zinc or of an alloy of zinc and aluminum, said method comprising the step of treating said surface with an aqueous solution having a pH of below 3 and comprising a complex formed from at least one species of metal oxo ion in conjunction with at least one species of hetero ion, the metal oxo ion being selected from the group consisting of molybdate, tungstate and vanadate; the hetero ion being selected from the group consisting of phosphorus (V), aluminium (III), silicon (IV), manganese (II), manganese (IV), zirconium (IV), titanium (IV), tin (IV), cerium (III) and nickel (II); and with a film forming acid tolerant resin compatible with the selected ions.