The kinetics of the recombination reaction FSO2 + O-2 -> FS(O-2)OO (1) has been studied at 298 K. FSO2 together with FSO3 radicals were generated by 193 nm laser flash photolysis of FS(O-2)O(O-2)SF. The measured rate coefficient at one atmosphere total pressure is k(1) = (4.6 +/- 0.6) x 10 (15) cm(3) molecule (1) s (1). Molecular properties for the FS(O-2)OO radical were calculated at the B3LYP/6-311+G(3df) and CCSD/6-311G(d) levels of theory. Consistent with the measured k(1) value, different density functional theory and GAUSSIAN-3 calculations predict an electronic energy barrier for reaction (1) close to 3 kcal mol (1). (c) 2008 Elsevier B.V. All rights reserved.