ZnS quantum dots with mercaptoacetic acid as a stabilizer were synthesized. The quantum dots had a diameter of less than 4 nm and a band gap of about 4.2 eV. The effect of refluxing time on the preparation of these samples was measured using. UV-Vis absorption and photoluminescence. The UV-Vis absorption and photoluminescence phenomena results show that the band edge emission is improved by increasing the refluxing time. (C) 2003 Elsevier Science B.V. All rights reserved.