The nonstoichiometric strontium-iron oxide SrFeO3-delta (2.5 less than or equal to 3 - delta less than or equal to 3.0) exhibits richness of equilibrium states over a broad range of temperatures and oxygen partial pressures. Its oxidation induced by ball milling was investigated. The mechanical treatment of the material at room temperature in oxygen atmosphere was found to cause the reaction. However, the product differs from compounds obtained by annealing, due to crystal imperfections introduced by milling: The changes in the oxygen stoichiometry, the crystal structure, and the morphology of the powder are discussed.