Surface modification is an approach used to protect materials, especially to prevent corrosion. For this, some methods are used: dry coating (thermal spraying, sputtering, cold spraying) and wet coating techniques to form covalent bonding (“grafting from”, “grafting to”) or non-covalent bonding (electrochemical, electrodeposition, layer-by-layer, freeze-drying, casting, sol-gel). The formation of covalent bonds allows a more stable protective layer. This talk reports on the relationship between processing, characterization and biological performance of thin films e.g. poly(methyl methacrylate) (PMMA) and poly(butyl methacrylate) (PBMA) on titanium (Ti), alloys based on zinc (Zn) and magnesium (Mg). These combinations are expected as a solution for as promising biodegradable medical devices. The “grafting from” method has been developed for covering: (i)Ti-based plates by P(MMA-co-BMA) layers to built-up craniofacial prosthesis and replace the bone to enhance the formability of the prosthesis and (ii)alloys based on Zn and Mg by PMMA layer to improve corrosion resistance.