The dynamics of three decomposition channels of the mercapto cation (CH3SH+) were investigated by classical trajectories and RRKM formalisms. The three channels are (I) CH bond dissociation through a "tight" transition state, (II) CS bond cleavage, and (I:II) SH bond scission. These calculations were performed with an analytical potential energy surface constructed from theoretical and experimental data available in the literature. The relative yields of CH3+ and CH2SH+ products are in qualitative agreement with charge-exchange experiments. The dynamical calculations revealed that the system is intrinsically non-Rice-Ramsperger-Kassel-Marcus (RRKM) at the energies selected in this study. Under nonrandom initial conditions, the system showed strong mode specificity, which may be rationalized by weak couplings between the low- and high-frequency modes, particularly the CH3 stretching normal modes, which is consistent with collisional activation studies. The classical trajectory calculations revealed an inverse isotope effect for both the CS and SH scission channels and a normal isotope effect for the CH bond dissociation process. Finally, we have found that molecular rotation decreases the mercapto cation decomposition rate and that orbital angular momentum dramatically modifies the relative yields of CH3+ and CH2SH+ products.