Bronze cultural heritage exposed to the outdoor environment is susceptible to degradation due to the corrosive effects of moisture and air pollution. In practice, various methods of corrosion protection of bronze and bronze patina are used, but due to the specific requirements of the conservation profession, the choice of these methods is limited, and they are often characterized by insufficient durability of the achieved protection. It is therefore necessary to develop new and improved methods of their protection. With this aim, the possibility of using long-chain phosphonic acids for corrosion protection of a bare and patinated bronze surface, as well as for improving the adhesion and protective properties of transparent organic coatings on these substrates was examined in this work. Given that the method of organic film formation can influence on its structure and stability, obtaining phosphonic acid films on a clean bronze surface by brushing, spraying and dip coating was investigated. The brushing and spraying methods, which are more practical for use on sculptures, produce films with slightly greater stability in a corrosive medium, however more reproducible and well-organized films are obtained by the dip coating method, so this method was used for further investigations. The influence of chain length and the terminal functional group of phosphonic acid on the crystallinity and protective properties of the self-assembled films was also investigated. It was found that acids with a longer chain form more ordered films, while acids with a shorter chain form film with a lower degree of order. Despite the lower crystalinity of the film, the acid with a shorter chain provides a high degree of protection when a sufficient film thickness is achieved. In the next step, the influence of the composition of the bronze substrate on the formation of self-assembled films of phosphonic acid was examined. The research was conducted on substrates made of zinc, tin and copper, the most common alloying elements in bronze, and on three types of bronze. It was found that protective films can be formed on all substrates, but their effectiveness and stability depend on the corrosion stability of the substrate. Substrates that are less corrosion resistant are protected for a shorter period of time, as the dissolution of the substrate leads to the dissolution of the protective film. In this work, selected phosphonic acids were also tested as molecular promoters of the adhesion of two acrylic and one polyurethane coating on pure bronze. Before applying the coating, the bronze was treated with phosphonic acids. Different methods were tested to remove the weakly bonded upper layers of the film in order to improve the adhesion of the coating. Phosphonic acids improved the protective properties and adhesion of the acrylic coating Paraloid B72 and the polyurethane coating, and inhibited the dissolution of the bronze. Finally, it was shown that self-assembled films of phosphonic acid contribute to the corrosion protection of patinated bronze exposed to a corrosive medium and improve the protective properties of Paraloid B72 on such surface. The corrosion protection provided by the studied systems was examined by electrochemical tests (polarization measurements and electrochemical impedance spectroscopy) on samples exposed to the corrosive effect of artificial acid rain. Some of the samples were additionally exposed to the effect of the outdoor urban atmosphere and to aggressive conditions in a humid chamber with NO2. The surface appearance of the samples before and after exposure to the corrosive medium was characterized by electron and optical microscopy. The structure of the films and their binding to the surface were examined by spectroscopic methods (FTIR, XPS, SFG) and TOF-SIMS spectrometry. In addition, the modified bronze surfaces were characterized by goniometry. The adhesion of the coating to the bronze substrate was determined based on a pull-off test.