Several SBA-15 silica materials with different pore structures were synthesized and functionalized with poly(ethyleneimine) (PEI). The as-prepared materials were characterized by XRD, SEM, TG, FT-IR, and N-2 physisorption techniques followed by testing for CO2 capture using a N-2 stream containing 15.1 v/v% CO2 in the temperature range of 30 75 degrees C. The results showed that the CO2 adsorption capacity linearly increased with the total pore volume of the SBA-15 phases in the tested temperature range (R-2 > 0.94). Temperature also showed a strong influence on CO2 adsorption capacity. SBA-15 material with the largest pore volume (1.14 cm(3) g(-1).) exhibited the largest CO2 adsorption capacity (105.2 mg g(-1) adsorbent) with 15.1 v/v% CO2 in N-2 at 75 degrees C and atmospheric pressure. Pore size was found not to be the main factor influencing the CO2 adsorption capacity of these PEI-modified SBA-15 materials. Adsorption-desorption cycles (12) revealed that the adsorbents with PEI loaded inside the pore channels were found to be quite stable, as they retained their CO2 adsorption capacity with many cycles.