The mixed (oxygen ionic-electronic) conductor bismuth vanadate (BiVO4) was studied with respect to its electrochemical properties. The ionic transference numbers, measured by the concentration cell method in the temperature range of 800 to 1000 K, vary from 0.7 to 0.3. The total conductivity of this ceramic material isone order of magnitude lower than found for cubic yttria-stabilized zirconia (YSZ). The activation enthalpy for the electronic conductivity is high (193 kJ/mol) compared to the ionic conductivity (71 kJ/mol). The PO2 dependence of the conductivity data in combination with the Seebeck measurements showed electrons to be the majority charge carriers, indicating that BiVO4 is an n-type mixed conductor.