The author discusses the effect of various deteriorating agents on metal art objects. The corrosion phenomena on the surface of metal antiquities is explained on the basis of electro-chemical reactions. The problematic and aesthetic aspects of conservation treatments such as retention of noble patinas are considered. Special reference is made to the conservation of excavated antiquities, and exposed monuments such as iron beams and pillars. The modern technique of conservation based on gas plasma reaction and the use of corrosion inhibitors in controlling corrosion are described. -- AATA