Thermoelectric power data were determined for undoped and 1 at% Ti-doped TZP specimens within the temperature range 922 to 1076 K and the oxygen partial pressure range between 10(-16) Pa and 100 kPa. The observed pressure and temperature dependences are related to the variation in the partial molar entropy of oxygen in the gas phase. The transported entropy of oxygen ions Sb-O-2(*) in the solid electrolyte is estimated to be 15 JK(-1) mol(-1).