B-site substituted perovskite-type SrTiO3-based ceramics are the most studied n-type oxide materials for thermoelectric applications. Sintered ceramics samples of Nb and Ta co-doped bulk SrTiO3 with the general formula SrTi1-x-yNbxTayO3(x = 0.0–0.1, y = 0.0–0.1) were prepared by solid-state reaction method at 1823 K in reducing atmosphere. All Nb/ Ta substituted and co-doped samples prepared in this study showed a single phase without much change in the lattice parameter and unit cell volume due to similar ionic radii of Nb and Ta. Electrical conductivity was highest in the Nb, Ta co-doped samples, where the concentration of the dopants was equal. However, the maximum thermoelectric power factor (PF) value was obtained for Nb-doped STO samples. The value of PF was about 250 µWm-1K-1at around 900 K. The Ta doping showed metallic nature, whereas the Nb doping showed semiconductor behavior.