Abstract The typical skutterudite structure compound CoSb 3 was prepared by arc melting followed by sintering. The samples were characterized by powder X-ray diffraction method, electron probe microanalysis (EPMA), and the thermoelectric properties such as the thermal diffusivity, electrical resistivity, and Seebeck coefficient were measured in the temperature range from room temperature to about 750 K. The thermal conductivity of CoSb 3 was estimated from the heat capacity, the experimental density, and the thermal diffusivity measured by the laser flash method. The calculated dimensionless figure of merit, ZT of CoSb 3 was lower than that of state of the art thermoelectric materials. In order to enhance the ZT , it was attempted to reduce the lattice thermal conductivity of CoSb 3 . The electronic contribution to the thermal conductivity was estimated by Wiedemann–Franz law, and the lattice thermal conductivity was determined. It was found that the lattice thermal conductivity of CoSb 3 can be decreased, and ZT of CoSb 3 can potentially be enhanced.