Mechanochemical modification of previously synthesized LaFeO3 perovskite-type oxide by a high-energy ball milling was investigated to introduce Fe4+ ions or transform some Fe3+ into Fe4+ in LaFeO3. X-ray absorption fine structure studies revealed that the formation of Fe4+ ions into LaFeO3 perovskite has been achieved at first time by ball milling at room temperature without any additives or replacement of La3+ ions by some divalent cations. The structural model of Fe4+ containing LaFeO3 could be described as with a modified perovskite having equal amounts of La and Fe vacancies, which is supported by a good correlation between the results of Fe K-edge XANES spectra and O-2-TPD. The synthesis of Fe4+-containing LaFeO3 perovskite by ball milling was able to produce the O-2 adsorption capacity of nonsubstituted perovskite-type oxide.