Pathways for hydrogen abstraction (H-abstraction) by the NO3 radical from the SH and the CH sites of the CH3SH molecule have been found for the reaction of CH3SH + NO3. Energy evaluations of the stationary points indicate that H-abstraction exclusively occurs from the SH site via a reactant complex [CH3S(H)-ONO2] possessing a two-center three-electron (2c-3e) S-O bond. Two oxygen atoms of the NO3 radical are involved separately in the 2c-3e S-O bond and in H-abstraction from the SH site.