Insoluble Mo(W)-S-Cu cluster compound films with a metallic lustre of various shades and colours have been applied to copper surface to provide attractive finishes. The anticorrosive characteristics of the Mo(W)-S-Cu cluster compound films with and without various passivation treatments are investigated by using accelerated chemical corrosion tests, LSV, XPS and AES determination. The results indicate that the films are liable to be oxidized gradually when exposed to air and they provide poor protective effect against Cl- or H2S erosion to copper. Colour loss or change as well as film degradation will occur. After PMTA passivation, not only are the colours of the films stabilized, but film degradation is also prevented. The protection effect of PMTA on the films can be attributed to the formation of a layer of dense, insoluble and transient polymeric coordination compound film via reaction of PMTA with Cu(I) in the coloured films.