**4. Conclusions**

TiO2 films grown by MOCVD process were demonstrated to be effective for methyl orange dye degradation under UV irradiation. The films presented the formation of anatase phase, and surface morphology composed of rounded grains. The methyl orange dye does not degrade under UV radiation without the presence of the TiO2 photocatalyst. The best photocatalytic result occurred for the film with thickness of 468 nm, which exhibited 69% of dye degradation in 300 minutes. The results suggest that the morphology and structural characteristics influence the photocatalytic activity of the TiO2 films.
