The adsorption and desorption of CO2 and SO2 on an amine-grafted SBA-15 sorbent has been studied by in situ infrared spectroscopy coupled with mass spectrometry. CO2 adsorbed on an amine-grafted sorbent as carbonates and bicarbonates, while SO2 adsorbed as sulfates and sulfites. The CO2 adsorption capacity of the amine- grafted sorbent was almost twice as much as that of a commercial sorbent. The adsorption of CO2 in the presence of H2O and D2O shows an isotopic shift in the IR frequency of adsorbed carbonate and bicarbonate bands, revealing that water plays a role in the CO2 adsorption on amine- grafted sorbents. Although the rate of adsorption of SO2 was slower than that of CO2, the adsorbed S surface species is capable of blocking the active amine sites for CO2 adsorption. A temperature-programmed degradation study of the amine- grafted sorbent showed that the surface amine species are stable up to 250 degrees C in air.