Precoated galvanized steel sheets were submitted to Prohesion test (PT) and to outdoor exposure test (OT). The corrosion products were different in both cases: surprisingly greigite was detected in samples of Prohesion test. Goethite, lepidocrocite, pyrite and magnetite were also found in these samples and the presence of akaganeite cannot be discarded. On the other hand, goethite, lepidocrocite, magnetite, akaganeite and silicates were found in outdoor exposure samples. This study allows concluding that in the Prohesion G-85 test the corrosion mechanism is different from that in the marine atmosphere for the analyzed samples and could not be used to predict the performance of this type of outdoor exposed materials.