The reaction of CH3SCH3 with H has been investigated using ab initio molecular orbital theory. Two primary processes have been identified: abstraction channel leading to the formation of CH3SCH2 and H-2, and substitution channel resulting in the products of CH3SH and CH3. On the basis of ab initio calculation, the kinetic properties have been deduced using the canonical variational transition-state (CVT) with the tunneling correction. The results show that, at low temperature range, substitution is the major reaction channel, while abstraction channel will have more contribution to the whole reaction rate as the temperature increases. (c) 2005 Elsevier B.V. All rights reserved.