We investigated thermoelectric properties of La-doped SrTiO₃ in order to determine the optimum sintering temperature which maximized its power factor. We prepared samples using a combination of combustion synthesis and spark plasma sintering. Combustion-synthesized samples (Sr_1–xLa_xTiO₃, x = 0.08) were subjected to spark plasma sintering at temperatures from 1513 to 1663 K. We measured the thermoelectric properties of sintered Sr_0.92La_0.08TiO₃ from room temperature to 1073K. 1) The average grain size of sintered Sr_0.92La_0.08TiO₃ increased with the sintering temperature. The maximum average grain size was 23.5 μm for a sintering temperature of 1663 K. 2) Among the samples, the Sr_0.92La_0.08TiO₃ sample sintered at 1633 K showed the maximum power factor of 1.51 × 10^-3 Wm^-1K^-1 at 375 K. The power factor of the single crystals at room temperature, i.e., 1.47 × 10^-3 Wm^-1K^-2, was higher than that previously reported. 3) These results proved that it is possible to enhance the thermoelectric properties by increasing the sintering temperature. Further, we investigated the effects of sintering direction on the thermoelectric properties of combustion-synthesized Sr_0.92La_0.08TiO₃ . The combustion-synthesized samples were sintered well along the sintering direction; therefore, the electrical conductivity measured along the sintering direction was more than twice that measured along the direction perpendicular to the sintering direction. However, the Seebeck coefficient was never affected in the experimental temperature range. Therefore, we concluded that 4) sintering direction affected particularly the electric properties of combustion-synthesized Sr_0.92La_0.08TiO₃.