SnO_2 NPs were successfully prepared via a hydrothermal method. X-ray diffraction analysis con fi rmed the rutile tetragonal structure of SnO_2 NPs. The crystallite size increased from 1.18 to 5.06 nm with increasing the preparation temperature from 100 to 180 °C. The SEM photography of the products exhibited the agglomeration of the SnO_2 nanocrystals to large view particles, while TEM images con fi rmed the polycrystalline phase and crystallite size those analyzed from XRD. The UV–vis absorption of ethanol suspended SnO_2 NPs was measured. The optical band-gap energies(Eg) were signi fi cantly blue-shifted due to quantum con fi nement. Fluorescence spectra came to con fi rm this shift, where a clear shift in the maximum emission peak was observed. Stokes shift of SnO_2 nanocrystals was found to be crystallite size dependent. X-ray diffraction analysis of the rutile tetragonal structure of SnO_2 NPs. The crystallite size increased from 1.18 to 5.06 nm with increasing the preparation temperature from 100 to 180 ° C. The SEM photography of the products exhibit the agglomeration of the SnO 2 nanocrystals to large view particles, while TEM images con fi rmed the polycrystalline phase and crystallite size those analyzed from XRD. The UV-vis absorption of ethanol suspended SnO 2 NPs was measured. The optical band-gap energies (Eg) were signi fi cantly blue-shifted due to quantum con fi nement. Fluorescence spectra came to con fi rm this shift, where a clear shift in the maximum emission peak was observed. Stokes shift of SnO 2 nanocrystals was found to be crystallite size dependent.