CaO/Ca(3)A1(2)O(6) sorbents have been proved to be a promising sorbent for CO2 sorption. However, the sorbents still suffer from low CO2 sorption capacity. In this work, self-activation was generated via thermally pretreating CaO/Ca(3)A1(2)O(6) sorbents in CO2 atmosphere at various temperatures to enhance the CO2 sorption capacity of CaO/ Ca(3)A1(2)O(6) sorbents. Results showed that the thermally pretreated temperature plays an overwhelming role in the CO2 sorption capacity and stability of the CaO/Ca(3)A1(2)O(6) sorbents. Superior CO2 sorption capacity (8.01 mmol g(-1) for C9A1-650 at 500 degrees C) is achieved, which is 72% higher than that of C9A1 (no pretreatment sample). After 50 carbonation-calcination cycles, the CO2 sorption capacity of C9A1-650 still remained 20% higher than that of C9A1. The high CO2 sorption capacity is ascribed to the smaller CaO grain size (37.1 nm) and the higher surface area (13.1 m(2) g(-1)), resulting from the self-activation process. Meanwhile, the CO2 cyclic sorption stability is due to the small original surface free energy. Furthermore, the C9A1-650 sorbent is employed to use in sorption enhanced methane steam reforming process. It provides a H-2 concentration of 98.9% and CH4 conversion of 98.7%, presenting greatly potential in practical application.