A chromium-free aqueous treatment solution for coating metal surfaces is described. The treatment solution contains fluorocomplex ions of titanium and/or zirconium and molybdate ions, vanadium ions and one or more aromatic carboxylic acids with at least one carboxyl groups and at least two further functional groups, wherein the two further functional groups are selected from the group comprising carboxyl groups, hydroxyl groups, amino groups and nitro groups.