Thermoelectric properties of BiCuSeO have been finely tuned previously by doping cations on bismuth sites. Here thermoelectric properties of BiCuSeO with isoelectronic indium doping were investigated by experimental methods detailedly. We found that electrical conductivity was remarkably enhanced by isoelectronic indium doping in BiCuSeO system, which resulted from about sixfold increase of carrier mobility from 5.6 cm(2) v(-1) s(-1) to 31 cm(2) v(-1) s(-1) at room temperature. Furthermore, we obtained a maximum power factor up to 4.6 mu W cm(-1) K-2 in isoelectronic indium doping BiCuSeO at 800 K. Finally, the dimensionless thermoelectric figure of merit reached similar to 0.6 at 800 K in Bi0.925In0.075CUSeO.