This work presents a study of the temperature dependence on the electronic transport properties for p-type (Bi0.5Sb1.5Te3) and n-type (Bi1.5Sb0.5Te3) pellets prepared by spark plasma sintering from ball-milled powders. Seebeck coefficient and electrical resistivity displayed a metallic behavior in both samples in the temperature range from 20 to 300 K, resembling to the carrier transport of a degenerate semiconductor. The magnitude of the Seebeck coefficient of the n-type sample was lower than that p-type sample, which was attributed to bipolar conduction. That is, in the n-type sample lie an acceptor level and a donor level, generating simultaneously electrons and holes. The donor level that promotes the n-type conductivity in Bi1.5Sb0.5Te3 could be attributed to the SbBi antisite defect as reveled by crystalline cell simulations.