Fe-substituted Ba-hexaaluninates (BFA-x (x=1-3), x indicates Fe content) oxygen carrier (OC) were found to exhibit excellent sintering-resistance under cyclic redox atmosphere at 800 degrees C thanks to the reservations of the structure during the CH4 reduction step, thus preventing the agglomeration of particles during the subsequent reoxidation step. Lattice oxygen highly active for the total combustion of CH4 was observed in the hexaaluminate structure and its chemical state was influenced by Fe content. The highest amount of active O coordinated with Fe3+ in the mirror plane (O-Fe3+(M)) for the total combustion was reacted (0.77 mmol/g) for BaFe3Al9O19 hexaaluminate OC. As a result, it exhibited the best reactivity with the CH4 conversion of 83% and CO2 selectivity of 100%. Moreover, superior regeneration and recyclability was also obtained, which originated from the fully recovery of O-Fe3+(M) in the hexaaluminate structure. (c) 2015 American Institute of Chemical Engineers AIChE J, 62: 792-801, 2016