As a transition metal to be used for oxygen carrier, Sn-based oxides were expected to have high theoretical oxygen transfer

capacity and have potential, and despite the low melting point, cycle stability was secured by forming a Ca–Sn perovskite

structure. Nevertheless, it was also confi rmed that high structural stability leads to a lower oxygen transfer rate compared

to other oxygen carriers, that is, a relatively late reduction reaction completion time. In this study, in order to improve the

oxygen transfer rate in the reduction reaction of Ca–Sn oxygen carriers, it was confi rmed whether it was actually improved

by partially replacing Co and Ce at the Ca site and whether it was applicable as oxygen carriers. It was confi rmed that the

substances that partially substituted Ce did not improve the oxygen transfer rate, and at the same time, the oxygen transfer

capacity was partially reduced compared to CaSnO 3 . However, Ca 0.9 Co 0.1 SnO 3 reduced the reduction reaction time by 20%

compared to CaSnO 3 . These fi ndings suggest that Co is a promising candidate for improving the oxygen transfer rate of

CaSnO 3 -based oxygen carriers in CLC processes.