The preparation and characterization of nanocomposites composed of CdS nanocrystals in cross-linked polystyrene matrix were reported. The used matrix was commercial macroporous ion-exchange resins. Characterizations using transmission electron microscopy (TEM) and X-ray diffraction (XRD) show the nano-sized CdS crystals with an average size of about 9 nm. These nano-sized crystals can show the size-dependent UV-vis absorption and photoluminescence in comparison with bulk samples. (c) 2007 Elsevier B.V. All rights reserved.