Nano CdS has been prepared by solid state method at room temperature in the absence of any surfactants or dopants. It is characterized by powder X-ray diffraction, scanning electron microscopy (SEM) and diffuse reflectance spectroscopic techniques. It shows cubic structure with the particle size ranging about 20nm. It also exhibits a strong photocatalytic activity for the decomposition of methyl orange (MO) and rhodamine B (RB) under UV and sunlight irradiation. The result shows that CdS exerts greater photocatalytic activity for MO (83%) and RB (73%) under sunlight than UV light.