A reaction-based process developed for the selective removal of CO2 from a multicomponent gas mixture to provide a gaseous stream depleted in CO2 compared to the inlet CO2 concentration. The proposed process effects the separation of CO2 from a mixture of gases by its reaction with metal oxides. The Calcium based Reaction Separation for CO2 (CaRS-CO2) process consists of contacting CO2 laden gas with CaO in a reactor such that CaO captures CO2 by the formation of CaCO3. CaCO3 is regenerated by calcination leading to the formation of fresh CaO sorbent and the evolution of a concentrated stream of CO2. The “regenerated” CaO is then recycled for the further capture of CO2. This carbonation-calcination cycle forms the basis of the CaRS-CO2 process. This process also may use a mesoporous CaCO3 structure that attains >90% conversion over multiple carbonation and calcination cycles.