Abstract: ZnTe1-xSex (ZTS) semiconductor thin films at various contents (x = 0.0, 0.1, and 0.2) are deposited on glass substrates kept at room temperature by the thermal evaporation technique with a thickness of 500 nm. This study examines the effects of varying the Se content on the variables influencing ZTS thin-film solar cell properties. XRD analysis reveals that the ZTS thin films' structure is cubic and polycrystalline, with a preferred orientation of (111) at 2θ ≈ 25.25. The intensities of all the peaks rapidly increase, though they show the same tendencies. The crystallinity of the films becomes higher. Grain and crystalline diameters (from 8.46 to 41.25 nm) both increase as the (x) content rises. Furthermore, AFM was applied to studying the morphology and to estimate the surface roughness of the obtained films. All films were homogeneous and smooth, and the (RMS) roughness of the films increases with increasing (x) content. Consequently, the thin-film crystallite size increases. The optical characteristics of ZTS films were examined using a UV/visible spectrophotometer. These films had a direct gap that shrank as the x content increased, reaching its lowest value of 1.86 eV at x= 0.2. Also, the optical parameters, such as refractive index, were decreased with increasing (x) concentration, which makes them useful in the manufacture of solar cells.