Reaction of non-stoichiometric SrFeOx (2.5 less than or equal to x less than or equal to 3.0) with carbon dioxide induced by high temperature and mechanical energy was investigated. The high-temperature reaction route was found to convert SrFeOx to a mixture of SrFe12O19 and SrCO3 at temperatures below 1128 K under 0.98 atm Of CO2 pressure. The mechanical reaction carried out at room temperature causes a complete decomposition of SrFeOx to strontium carbonate and hematite via a metastable ferric carbonate phase. We examined the phase transformations, the reaction kinetics and morphology of carbonated SrFeOx, and compared the two processes. (C) 2002 Elsevier Science Ltd. All rights reserved.