Amorphous undoped TiO2 and Mo-doped TiO2 thin films were obtained by spray pyrolysis. By heat treatment, they became polycrystalline consisting in anatase, or mixed anatase/rutile phases, if deposited on glass or silicon, respectively. Mo enters in the TiO2 matrix as Mo5+, determining a slight red shift of the absorption edge. Based on Fourier transmission infrared analysis, performed on the studied films, before and after irradiation, providing information on the relationship between hydrophilicity and the amount of the adsorbed hydroxyl groups, we certify once again that the anatase phase (present in proportion of 100% in the films deposited on glass) is superior concerning the hydrophilic properties. Mo enhances wettability for the films deposited on silicon, compared to the undoped one, even if determines a rise in the rutile weight percentage, as a combined effect with the substrate nature. The decomposition of the oleic acid confirms that titania films with higher hydrophilic performances are also good photocatalysts, confirming in fact that investigating the hydrophilic properties of these films constitutes a much simpler way to obtain information on their photocatalytic activity.