The polycrystalline In2O3 ceramics doped with cobalt were prepared through the spark plasma sintering (SPS) process. Both thermoelectric transport properties and microstructure of the ceramics were investigated. The Co-doped In2O3 by SPS had a remarkable effect on the transport properties. Large electrical conductivity and thermopower was observed in dilute Co-doped sample. The maximum power factor were found in In1.98Co0.02O3 sample as 4.6 x 10-4 W center dot(m center dot K2)-1 at 1073 K with the ZT value up to 0.26.