In this work a surfactant-free microwave method for preparation of CdS nanoparticles is reported. The effect of different parameters i.e. time and irradiation power, sulfur source and solvent on the morphology and the samples particle size have been investigated. The synthesized nanostructures were characterized by X-ray diffraction, energy-dispersive X-ray analysis, scanning electron microscopy, Fourier transform infrared, photoluminescence and ultraviolet–visible spectroscopy.