Photo-degradation of synthetic dyes by cadmium sulfide nano-particles synthesized by micro-emulsion/arrested precipitation routes using thioglycolic acid; potassium pyrosulfate and disodium salt of ethylene diamine tetra acetic acid (EDTA) as capping agents have been investigated. Synthesized nanoparticles have been characterized by X-ray diffraction, thermo-gravimetric analysis, high-resolution transmission electron microscopy. BET surface area analysis and UV-Vis spectro-photometry. The synthesized cadmium sulfide nano particles are observed to be a mixture of cubic and hexagonal phases and have crystallite size and surface area of 3.7, 6.8 and 13.9 nm and 32.11, 29.54 and 8.63 m(2)/g for thioglycolic acid, potassium pyrosulfate and EDTA capping agents, respectively. As expected, the photo-catalytic efficiency of nano-particles for degradation of dyes is observed to increase with increase in surface area (decrease in particulate size). (C) 2011 Elsevier B.V. All rights reserved.