In this article, the authors report synthesis of CdS nanoparticles using a simple, inexpensive and straightforward chemical colloidal method using organic and inorganic capping agents. 1-6 hexanedithiol, mercaptoethanol, thioglycerol, tetraethyl orthosilicate, and tetraethyl orthotitaniate are used as the capping agents. The optical absorption spectra of CdS nanoparticles synthesized using the same parameters are found to depend on the nature of capping agents. The infrared absorption measurements provided important information about the nature of bonding. The optical studies on effect of x-ray irradiation on thioglycerol-capped CdS nanoparticle are also discussed. (C) 2008 American Vacuum Society.