Microporous activated carbon spheres (ACSs) with a high specific Brunauer-Emmet-Teller (BET) surface area were prepared from resole-type spherical crosslinked phenolic beads (PBs) by physical activation. The PBs used as precursors were synthesized in our laboratory through the mixing of phenol and formaldehyde in the presence of an alkaline medium by suspension polymerization. The effects of the gasification time, temperature, and flow rate of the gasifying agent on the surface properties of ACSs were investigated. ACSs with a controllable pore structure derived from carbonized PBs were prepared by CO2 gasification. Surface properties of ACSs, such as the BET surface area, pore volume, pore size distribution, and pore diameters, were characterized with BET and Dubinin-Reduchkevich equations based on N-2 adsorption isotherms at 77 K. The results showed that ACSs with a 32-88% extent of burn-off with CO2 gasification exhibited a BET surface area ranging from 574 to 3101 m(2)/g, with the pore volume significantly increased from 0.29 to 2.08 cm(3)/g. The pore size and its distribution could be tailored by the selection of suitable conditions, including the gasification time, temperature, and flow rate of the gasifying agents. The experimental results of this analysis revealed that ACSs obtained under different conditions were mainly microporous. The development of the surface morphology of ACSs was also studied with scanning electron microscopy. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 3283-3291, 2008