The effects of the oxygen potential gradient (dµO) on mass transfer via grain boundaries (GBs) in the thickness direction of polycrystalline alumina films were investigated using an oxygen permeation technique at 1873 K. These trials employed gaseous 18O2 in conjunction with undoped, Y-doped or Hf-doped alumina wafers as models for antioxidative films. The 18O concentration distribution over the entire wafer thickness was evaluated in conjunction with the application of a dµO.The GB diffusion coefficients for oxide ions (DO_gbδ) near the wafer surfaces in the absence of a dµO decreased in the order of undoped, Hf-doped and Y-doped. In the case of the undoped wafer, the diffusivity of oxide ions was inhibited near both surfaces with the application of a dµO. In contrast, that in the Y-doped wafer was not inhibited near either surface when applying a dµO. The results obtained for the Hf-doped wafer were intermediate between those for the undoped and Y-doped wafers, such that the diffusion of oxide ion was not suppressed near the PO2(hi) surface but was suppressed at the PO2(lo) surface.The movement behavior of oxide ions in undoped, Y-doped and Hf-doped alumina wafers under a dµO was investigated in relation to changes in the electrical characteristics toward the thickness direction.