The reaction pathways of sulfur tetroxide (SO4 (C2v)) with OH radical have been investigated at the MP2/6-31++G(d,p) and G3MP2B3 levels. The mechanism I (Transfer of O-atom and the dissociation of SOO ring) and II (Dissociation of SOO ring and transfer of O-atom) has been investigated for title reaction. Our calculations result shows that mechanism II is more feasible than mechanism I under ordinary conditions. The values of rate constant for mechanism II of the SO4 (C2v) + OH reaction are calculated at the temperature range of 200–1,400 K. These values clear that the importance of SO4 (C2v) + OH reaction through mechanism II increases with increasing temperature and, this reaction plays important role in formation of acid rain in high temperatures.
