Chemical looping air separation (CLAS) is an air separation technology with a relatively small energy footprint. In this contribution, the kinetic study of Mn-based oxygen carriers has been carried out in a CLAS process. The O2 release behavior was investigated under Ar in a fixed bed. Results showed O2 release amounts increase gradually with an increasing temperature. Moreover, fitting various gas-solid reaction mechanisms with the experimental data was used to obtain the chemical reaction kinetics for MnO2 and Mn2O3 for O2 release. As for all involved gas–solid reaction mechanisms, the first-order chemical reaction model (C1) and Avrami–Erofe’ev random nucleation and subsequence growth model (A2) fitted well with O2 release experimental data for MnO2 and Mn2O3, respectively. Furthermore, activation energy, pre-exponential factor and reaction order were also determined for these models.