SnO 2 quantum dots were successfully prepared via chemical precipitation assisted by ultrasound. X-ray diffraction analysis confirmed the rutile tetragonal structure of SnO 2 QDs with a crystallite size of 1.4 nm. The SEM micrographs of the obtained powder exhibited that the SnO 2 QDs are agglomerated particles of around 10 nm, while TEM images confirmed that the crystallite size are similar to the measured from XRD. The band-gap energy of the SnO 2 QDs measured from the UV-Vis reflectance spectrum of the SnO 2 QDs was 4.3 eV, displaying a significantly blue-shifting attributed to quantum confinement.