Cadmium selenide nanocrystals were grown over silica surfaces using a one-step synthetic method involving the thermal degradation of the single-molecule precursor [Cd(Se2CNEt2)(2)], Et=C2H5. The X-ray powder diffraction patterns for the SiO2/CdSe nanocomposites show diffraction peaks consistent with the presence of hexagonal-CdSe. Scanning and transmission electron microscopy show inorganic composite particles formed by islands of Use nanocrystals at the SiO2 surfaces. A series of SiO2/CdSe particles were obtained in which the samples show quantum size effects in their optical spectra. (c) 2005 Elsevier B.V. All rights reserved.