Bronze art works and cultural heritage are exposed to everyday pollution present in outdoor or indoor atmosphere. Because of that, they are subjected to corrosion processes that can lead to changes in their appearance and stability and chronic decay of material, which then cause material repair or replacement costs. Such objects are therefore often covered with patina, which has aesthetic and / or historical value. Patina on bronze sculptures protects the base metal and enhances the aesthetics of the artwork itself. One of the possibilities of protecting bronze surfaces is the modification of the surface with a thin film of organic molecules. The aim of this study was to examine the possibility of protecting patinated bronze from corrosion caused by acid rain, using self-assembled monolayers long-chain phosphonic acids. Tests were conducted in a solution that simulates acid rain at pH 5. The properties of untreated and treated surfaces under different conditions affecting the formation of self-assembled monolayers and various protection methods have been compared. The protective effect of the obtained thin films was confirmed by electrochemical assays, linear polarization method and electrochemical impedance spectroscopy. In order to obtain qualitative and quantitative information on the obtained protective layer, a Fourier transformation infrared spectroscopy was also performed. Given the results obtained, the existence and effectiveness of the protective film of 16-phosphonohexadecanoic acid on patinated bronze has been confirmed. The durability of the obtained protection significantly depends on the conditions and method of preparation of the protective film.