This paper describes the development of nanostructured thin films of TiO2 and Ag:TiO2 with different Ag loading content and with various number of layers by the polymeric precursor method, in order to test them in the photocatalysis of the degradation of textile dyes, using rhodamine B as a standard. Analysis of the films showed that the adopted method could be used to synthesize pure anatase and the silver-decorated phase. Moreover, 0.25% Ag:TiO2 thin film showed enhanced photocatalytic efficiency. The tests with film of different thickness showed that for pure TiO2, the increase in film thickness was the only factor responsible for improving the photocatalytic activity, whereas for the Ag:TiO2 thin films, the increase in photocatalytic activity was related to associate effects: the electron transfer from TiO2 to Ag, reducing the electron–hole recombination, and the increase in film thickness.