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The n-type Bi2Te2.7Se0.3 and p-type Bi0.5Sb1.5Te3 compounds were fabricated by using a spark plasma sintering technique after ball-milling a solidified ingot. Both the n-type and the p-type ingots exhibited low oxygen concentrations of 0.035 at.%. After pulverizing, the oxygen concentrations of both the n-type and the p-type powders considerably increased up to 1.836 at.% and 1.520 at.%, respectively. Due to hydrogen reduction, the oxygen concentrations of the n-type and the p-type powders decreased to 0.196 at.% and 0.234 at.%, respectively. The figure-of-merit Z of the sintered n-type compounds by using hydrogen-reduced powders was found to be remarkably improved up to 2.37 × 10−3 K−1, compared with that of sintered n-type compounds by using non-reduced powders (1.32 × 10−3 K−1) because of the removal of oxygen, which acted as a donor. However, the figure-ofmerit Z of the sintered p-type compounds by using hydrogen-reduced powders somewhat increased from 2.72 × 10−3 K−1 to 3.09 × 10−3 K−1. The p-type thermoelectric compounds are believed to be not significantly affected by hydrogen reduction.