Polycrystalline samples of La1−xAxCoO3 (A=Pb, Na) were prepared and their electrical and thermal transport properties are reported in the temperature range of 300 to 600 K. All samples show semiconducting behavior. The parent compound LaCoO 3 undergoes a sign change in the Seebeck coefficient at about 400 K from negative to positive with increasing temperature, while Pb and Na doped samples show large positive Seebeck coefficients indicating a p-type conduction in the whole temperature range studied. The thermal conductivity increased with increasing temperatures for all samples arising from increased electrical conductivity as the temperature is raised. The lattice part of the thermal conductivity is suppressed significantly upon Pb substitution. A promising thermoelectric figure-of-merit (ZT) around 0.2 has been achieved for La 0.9 Pb 0.1 CoO 3 at 575 K.