In order to detect oxygen diffusion in electrolyte materials in Solid Oxide Fuel Cells, we here want to propose a muSR experiment on three oxide electrolytes exhibitng good oxygen ionic conductivity at high temperatures. The principle behind the proposed experiment is that the implanted positive muons locate at the vicinity of O^{2-} ions so as to make a stable O-mu; bond in the electrolyte materials. Then, as temperature increases from room temperature, both O^{2-} and [Omu]^{1-} start to diffuse above a certain temperature. Since the O^{2-} ions diffuse through the channel formed in the cation lattice, namely, in the rigid skeleton, we could see the [Omu]-diffusion through the change in both the hopping rate and field distribution width, if the skeleton has a nuclear magnetic field. Note that oxygen diffusion is not detected by neutron and NMR mea