In this study, the laser processing of thermally annealed TiO₂ thin films at 420 ℃ in hydrogen atmosphere, utilizing an pulsed fourth-harmonic generation Nd: YAG laser employing different laser intensities in the atmosphere at room temperature, has been reported. Further, the surface morphology and crystalline structure have been investigated by means of atomic force microscopy [AFM], X-ray diffraction [XRD], Raman analysis. The AFM images obtained show that the film’s surface changes as the effect of the laser processes. Moreover, XRD and Raman analysis of the TiO₂ thin films indicate at the threshold laser intensity, I_th = 66 MW/cm² of the fourth-harmonic generation Nd: YAG laser phase transition from atanase-rutile to a crystalline 100% rutile.