A process is described for treating metal surfaces with a composition comprising an oxidizer, an acid, a corrosion inhibitor, an unsaturated alkyl substituted with an aromatic or non-aromatic cyclic groups, and optionally but preferably a source of adhesion enhancing species selected from the group consisting of molybdates, tungstates, tantalates, niobates, vanadates, isopoly or heteropoly acids of molybdenum, tungsten, tantalum, niobium, vanadium, and combinations of any of the foregoing, an organic nitro compound, and a source of halide ions in order to increase the adhesion of polymeric materials to the metal surface.