Production of O2−CO2 mixed gases for the oxyfuel combustion using a Co-based oxygen carrier packed in a fixed bed reactor was investigated. The reaction kinetics of CoO with O2 and the decomposition kinetics of Co3O4 in CO2 atmosphere at different temperatures were studied using thermogravimetric analysis (TGA). Both desorption and sorption processes exhibit a high reaction rate. Multiple sorption and desorption cycles indicated that Co-based oxygen carrier has high reactivity and cyclic stability. The results of X-ray diffraction indicated that Co-based oxygen carrier does not react with CO2 during the desorption stage, and this is especially important for oxyfuel combustion. The high temperature sorption process for production of O2−CO2 gas mixtures in a fixed bed reactor packed with Co-based oxygen carrier particles through air separation with carbon dioxide as the purge gas is investigated. Oxygen is absorbed, and heat is stored by the Co-based oxygen carrier particles with air being fed. An O2−CO2 stream can be obtained when the fixed bed is regenerated with carbon dioxide as the desorption gas. O2 fraction in the O2−CO2 gas mixtures can be controlled by adjusting the flow rate of CO2 regeneration gas. This Co-based oxygen carrier offers potential for further study in the O2−CO2 production for the oxyfuel coal combustion process.