The polycrystalline SrTiO3 thin films were prepared by the sol-gel-hydrothermal method on glass substrates. The synthesis pathway was initiated by preparing a clear TiO2 solution using the sol-gel method. This clear solution was then deposited on a glass substrate using the dip coating technique, followed by the transformation of a thin layer of TiO2 into SrTiO3 by the hydrothermal method. The crystal structure, bond interactions, and band gap energy of SrTiO3 thin layers were characterized using X-ray Diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), and UV–Vis Diffuse Reflectance Spectroscopy (UV-DRS). The XRD patterns of all SrTiO3 thin layers indicated the perovskite structure of the samples. The FTIR spectrum showed an interaction of the silanol groups on the surface of the glass substrate with Ti–O–Ti of SrTiO3 layers. The characteristics of the UV-DRS spectrum were influenced by the thickness of the SrTiO3 layer formed on the glass substrate. The findings of this work provide insights for producing SrTiO3 layers with specified thickness and morphology.