In the present study, we intend to evaluate the effect of temperature on the structural, morphological, and optical properties of tin oxide. For this purpose, tin oxide micro-flowers were prepared by the hydrothermal method at two different hydrothermal temperatures of 130 and 150°C. The synthesized samples were investigated and characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Ultraviolet–Visible Spectroscopy (UV-Vis). The XRD results showed that the synthesized samples have single-phase crystallinity with a rutile structure. The mean crystallite size for synthesized Micro- flowers was calculated by the Debby-Scherrer equation and the values were 21 and 28 nm for 130 and 150°C respectively. The results of FESEM showed the morphology of tin oxide is Micro-flower for both temperatures and increasing the temperature from 130 to 150°C caused the morphology of tin oxide samples to change from Micro-flowers consisting of nanoparticles to Micro-flowers consisting of nanoplates. The optical bandgap was increased, whereas the refractive index decreased by increasing temperature from 130 to 150°C.