Zn and Ge co-doped In2O3-based ceramics have been prepared by the spark plasma sintering (SPS) technique. Microstructure studies show that dense and fine-grained ceramic samples can be obtained at low temperature sintered by SPS, and the grain size is about 100-300 nm. These In2O3-based ceramics show higher electrical conductivity (similar to 10(3) S/cm) as compared with the pure In2O3 (similar to 50 S/cm). In addition, the samples also exhibited large power factor, especially the In1.98Zn0.01 Ge0.01O3 sample similar to 7.5 x 10(-4) W/mK(2). The evaluated maximum ZT value is 0.20 at 973 K, which makes them promising materials to be used in thermoelectric devices.