Many methods of corrosion protection rely on toxic chemicals such as hexavalent chromium (Cr6+), which is the species responsible for protection in conversion coatings, anodizing baths and as a pigment in polymer coatings. Despite many attemps to replace Cr6+ and other harzardous chemicals in corrosion protection, very little progress has been made. Passive layers containing Ce and Mo have already been formed on materials such as A17075 and A12024, and their corrosion behaviour has been shown to improve by inhibition of both anodic and cathodic reaction. In this work the results of applying these coatings to SS304 and 316 will be presented. The layers were studied by electrochemical impedance spectroscopy (EIS), X-ray photo-electron spectroscopy (XPS), and the corrosion behaviour was followed by EIS and d.c. current methods.