Binary skutterudite CoSb(3) nanoparticles were synthesized by solvothermal method. The nanostructuring of CoSb(3) material was achieved by the inclusion of various kinds of additives. X-ray diffraction examination indicated the formation of the cubic phase of CoSb(3). Structural analysis by transmission electron microscopy analysis further confirmed the formation of crystalline CoSb(3) nanoparticles with high purity. With the assistance of additives, CoSb(3) nanoparticles with size as small as 10 nm were obtained. The effect of the nanostructure of CoSb(3) on the UV-visible absorption and luminescence was studied. The nanosized CoSb(3) skutterudite may find application in developing thermoelectric devices with better efficiency.