Cadmium sulfide (CdS) nanocrystals were successfully prepared in inverse microemulsion under gamma-irradiation at room temperature. Their shape can be controlled by changing the surfactant concentrations and the addition of hydroxyethyl cellulose (HEC)as the template. Cds nanorods were successfully obtained under gamma-irradiation using HEC as the template, which was confirmed by the observation of transmission electron microscopy (TEM). Without the addition of HEC, spherical US crystals were formed. X-ray powder diffraction (XRD) pattern and electron diffraction (ED) analysis showed the hexagonal lattice of US in the nanorods. Additionally, the optical properties of US nanorods were characterized by ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy. (c) 2006 Elsevier B.V. All rights reserved.