The CO2 adsorption properties of an ethylenediamine-modified mesoporous silica, EDA-SBA-15, have been examined. Adsorption isotherms were collected by TGA measurements, and the breakthrough time and adsorption capacity were measured using a fixed-bed flow system. The EDA-SBA-15 sorbent adsorbs around 20 Mg/g of CO2 from 15% CO2 in N-2 at 25 degrees C and 1 atm total pressure. In pure CO2 at 1 atm, its adsorption capacity is 86 mg/g at 22 degrees C. The EDA-SBA-15 sorbent is fully regenerable by thermal swings during cyclic adsorption/desorption. Desorption of CO2 occurs at 110 degrees C on EDA-SBA-15 and the sorbent is stable in air up to 200 degrees C. The CO2 uptake by EDA-SBA-15 is not influenced by humidity. The adsorption capacity data are compared with those of previously reported amine-modified silica sorbents.