Green synthesis of SnO2 quantum dots (QDs) was developed by microwave heating method using the amino acids, namely, aspartic and glutamic acid. This method resulted in the formation of spherical SnO2 quantum dots with an average diameter less than the exciton Bohr radius of SnO2. The average diameter of Sn02 quantum dots formed using glutamic acid is -1.6 nm and is smaller than that formed using aspartic acid (similar to 2.6 nm). In the electronic spectra, a clear blue shift in the band gap energy from 4.33 to 4.4 eV is observed with a decrease in particle size (2.6-1.6 nm) due to three dimensional quantum confinement effects. The synthesized SnO2 QDs were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED). X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FrIR). The optical properties were investigated using UV-visible spectroscopy. The synthesized SnO2 QDs act as an efficient photocatalyst in the degradation of Rose Bengal and Eosin Y dye under direct sunlight. For the first time, Rose Bengal dye was degraded using SnO2 QDs as a photocatalyst by solar irradiation. (C) 2015 Elsevier Inc. All rights reserved.