Single-step green synthesis of ZnSe quantum dots (QDs) from 1,2,3-selenadiazole and zinc acetate resulted in formation of high-quality mono-disperse ZnSe with engineered band-gap. The present method is a non-TOP green route where oleic acid is used as a surfactant. The size quantization effect can be monitored by UV-visible spectroscopy which shows in the range 370-387 nm (3.20-3.35 eV), a blue shift of about 70-90 nm with respect bulk ZnSe. Photoluminescence measurement revealed band-gap emission at similar to 390 nm (3.18 eV, Stokes shift of <10 nm with FWHM <30 nm). Broadened XRD pattern indicated formation of cubic ZnSe and the estimation of particle size from the line broadening at < 1 1 1 > matched well the TEM analysis. (C) 2009 Elsevier B.V. All rights reserved.