A quasi-classical trajectory study of the title reaction is reported using a global, double, many-body expansion potential energy surface for HSO 2 . Calculations are presented for specific translational energies and rovibrational states of the reactants, showing that formations of H + SO 2 and HS + O 2 are the most favored processes, although other products are also formed. The reaction is predicted to be barrier free and its mechanism is discussed, with reaction rate constants also being reported.