In this work, the impact of changing the flow rate of oxygen from 1 to 5 sccm in microstructure and optoelectronic properties of vanadium oxide (V_xO_y) thin films deposited by the reactive magnetron sputtering on glass substrates has been investigated. The films were analyzed for crystallinity using XRD, surface morphology using SEM, and the optoelectronic characteristics of the films using UV–Vis spectroscopy. The XRD spectra of the films exhibited good crystallinity and preferred orientation. In addition, structural parameters such as crystal size, stress, number of unit volumes of crystals, and displacement density were evaluated. Analysis of the XRD data indicated a phase transition from the monoclinic VO₂ phase to the orthorhombic V₂O₅ structure with increasing oxygen flow. A higher transmittance of the films was observed from the optical measurements which moved parallel to the increase in the oxygen flow …