The electrical properties of high-temperature TiO2 melts were evaluated using a modified floating zone furnace with four ellipsoidal mirrors and Ir electrodes. A droplet of molten TiO2 was suspended with two Ir electrodes. The resistivity of the molten TiO2 decreased in the reducing atmosphere, and with Ta2O5 doping. Thermoelectric power, up to 250 mV, due to the temperature difference at the electrodes, was observed in the specimens with and without Ta2O5 doping in Ar and/or 20% O-2-Ar atmospheres. The thermoelectric power of Ta2O5-doped TiO2 is slightly larger than that of non-doped TiO2. This phenomenon is discussed based on the Seebeck effect, the diffusion potential and/or the electrochemical potential. (C) 2002 Elsevier Science B.V. All rights reserved.