This study was conducted with the aim of analyzing the crystal structure, surface morphology structure, and energy band gap values ​​in zinc oxide (ZnO), tin(IV) oxide (SnO2), and titanium dioxide (TiO2) thin films. This study uses an experimental research type that goes through two stages of work, namely synthesis and characterization of thin films. The synthesis stage is through the process of making sol-gel solutions, depositing solutions on substrate media, and heating thin film samples. While the characterization stage is carried out through three testing processes using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometry. The research data obtained were analyzed descriptively and presented in the form of images, tables, and graphs to see the quality and characteristics of the test samples. Based on the results of the analysis, it is known that the crystal structure of the ZnO thin film is hexagonal while SnO₂ and TiO₂ are tetragonal. The surface morphology of the SnO₂ and TiO2 thin films is granular, while the ZnO thin film is a nanorod. The smallest energy band gap value is found in the ZnO thin film with a value of 2.00 eV. There are four factors that affect the energy band gap value in thin films, namely precursor material, deposition method, substrate media, and dopant material.