Oxygen desorption/absorption behavior of In-substituted BaFeO 3Àd [BaFe 1Àx In x O 3Àd ] was evaluated using thermogravimetry, high-temperature X-ray diffraction, and iodometry. By In substitution of 10% into BaFeO 3Àd with ordered distribution of oxide ion vacancy, the structural change to cubic perovskite structure occurred, accompanied by the rearrangement of oxide ion vacancy in random and by the increase in the average valence of Fe ions. The amount of desorbed oxygen per Fe ion was enhanced by only 10% In substitution, which could be attributed to the random distribution of oxide ion vacancies. Among the In-substituted specimens with almost constant valence of Fe ion, BaFe 0.9 In 0.1 O 3Àd with the highest value of Fe content exhibited the largest amount of desorbed oxygen from the lattice, indicating that this material could be regarded as a promising candidate for oxygen storage materials. K E Y W O R D SBaFe 1Àx In x O 3Àd , high-temperature X-ray diffraction, oxygen desorption, perovskite-type structure, thermogravimetry

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