A process for functionalizing titanium metal surfaces with nanometric particles of titanium dioxide wherein: - the article to be functionalized is immersed in a suspension of nanometric particles of titanium dioxide; - when completely wetted the article is heated to remove the solvent; - the article is subjected to a thermal cycle in order to improve fixing of the nanoparticles to the treated surface, and wherein: said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: i) reacting a titanium alkoxide with a suitable complexing solvent; ii) distilling the solution derived from step i) until a small quantity results; iii) adding water together with said complexing solvent and one or more polycondensation inhibitors to the solution derived from step ii), then heating the reaction mixture under reflux to obtain the desired nanoparticulate dispersion or said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: - reacting a titanium salt under hot conditions in water in the presence of mineral acids and a non-ionic surfactant; - reducing the solution thus obtained to a small quantity. - the article to be functionalized is immersed in a suspension of nanometric particles of titanium dioxide; - when completely wetted the article is heated to remove the solvent; - the article is subjected to a thermal cycle in order to improve fixing of the nanoparticles to the treated surface, and wherein: said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: i) reacting a titanium alkoxide with a suitable complexing solvent; ii) distilling the solution derived from step i) until a small quantity results; iii) adding water together with said complexing solvent and one or more polycondensation inhibitors to the solution derived from step ii), then heating the reaction mixture under reflux to obtain the desired nanoparticulate dispersion or said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: i) reacting a titanium alkoxide with a suitable complexing solvent; ii) distilling the solution derived from step i) until a small quantity results; iii) adding water together with said complexing solvent and one or more polycondensation inhibitors to the solution derived from step ii), then heating the reaction mixture under reflux to obtain the desired nanoparticulate dispersion or i) reacting a titanium alkoxide with a suitable complexing solvent; ii) distilling the solution derived from step i) until a small quantity results; iii) adding water together with said complexing solvent and one or more polycondensation inhibitors to the solution derived from step ii), then heating the reaction mixture under reflux to obtain the desired nanoparticulate dispersion said suspensions of nanometric titanium dioxide are obtained by a process comprising the following steps: - reacting a titanium salt under hot conditions in water in the presence of mineral acids and a non-ionic surfactant; - reducing the solution thus obtained to a small quantity.