Electrical properties of In2O3-doped yttria-stabilized zirconia (In-YSZ) were investigated. The solubility limit of In2O3 in YSZ (10 mol% Y2O3) is 17.5 mol%. The total conductivity depended on the concentration of In2O3. The activation energy of In-YSZ was higher than that of YSZ. From the oxygen partial pressure (P-O2) dependence of the total conductivity of In-YSZ, the electronic conductivity increased with increasing In2O3 concentration at low oxygen partial pressures and at high temperature. From the results, we discussed the applicability of In-YSZ to a membrane for hydrogen production from direct water splitting at high temperature.