We report a quasi-classical trajectory study of the title reaction using a double many-body expansion potential energy surface for ground state HSO2. Calculations for specific low ro-vibrational states of the reactants, as well as thermalized reactants over the range of temperatures 1400 <= T/K <= 2200, have been performed. The calculated cross sections indicate a barrier-type mechanism, and nearly thermalized product distributions. Both HOSO and HSO2 isomers are formed in quite different instances during the collisional process. The rate constant is found to be enhanced by adding internal energy to the reactants, with the thermalized result being in good agreement with existing experimental data. (C) 2007 Elsevier B.V.. All rights reserved.