Aminopropyl-functionalized mesoporous silica microspheres (AF-MSM) were synthesized by a simple one-step modified Stober method. Dodecylamine (DDA) was used as the catalyst for the hydrolysis and condensation of the silica Source and as the molecular template to prepare the ordered mesopores. The mesoporous silica surfaces were modified to aminopropyl groups by the co-condensation of tetraethoxysilane (TEOS) with 3-aminopropyltriethoxysilane (APTES), up to a maximum of 20 mol.% APTES content in the silica source. The particle size, Brunauer-Emmet-Teller (BET) specific surface area, and mesoporous regularity decreased with increasing APTES content. It is believed that this result is caused by a decreasing amount of DDA incorporated into AF-MSM with increasing APTES content. It was also confirmed that the spherical shape and the mesostructure were maintained even if 20 mol.% of APTES was added to the silica source. Moreover, AF-MSM was applied to the CO2 adsorbent. The breakthrough time of the CO2 and CO2 adsorption capacities increased with increasing APTES content. The adsorption capacity of CO2 for AF-MSM, prepared at 20 mol.% APTES, was 0.54 mmol g(-1). Carbon dioxide adsorbed onto AF-MSM was completely desorbed by heating in a N-2 purge at 423 K for 30 min. (C) 2009 Elsevier Inc. All rights reserved.