In this study, the thermoelectric power and resistivity of the perovskite manganite $La_{0.75}Ba_{0.25}MnO_3$ were investigated in the temperature range 300K-1200K. The electrical resistivity and thermoelectric power indicate a transport mechanism dominated by adiabatic small-polaron hopping. The power factor increases from $2{ imes}10^{-6}W/mK^2$ to $1{ imes}10^{-5}W/mK^2$ as to the temperature increases from 400K to 1200K, which indicates that the compound is highly feasible as a thermoelectric material at high temperatures.