This paper systematically investigates the roles of lattice oxygen in V2O5 and activated coke over coke-supported V2O5 catalysts in SO2 removal process at 200 degrees C. The results show that one SO2 molecule reacts with one O atom in a surface V2O5 molecule to form an intermediate (a VOSO4-like structure), which then reacts with gaseous O-2 to form sulfur species (SO3 or H2SO4 in the presence of H2O) and V2O5. The SO3/H2SO4 migrates over the coke surface and stores in the pores in the vicinity Of V2O5 sites. Mineral matters, oxygen and nitrogen species in the activated coke are unfavorable to migration of SO3/H2SO4. The pores effective for storage of SO3/H2SO4 are those less than 1 nm in size. (C) 2008 Elsevier B.V. All rights reserved.