The effects of collision energy (E col) and five different H2CO+ vibrational modes on the title reaction have been studied, including measurements of product ion recoil velocity distributions. A series of ab initio and Rice-Ramsperger-Kassel-Marcus calculations were used to examine properties of various complexes and transition states that might be important. Four product channels are observed. Proton transfer (PT) dominates at low E-col, and is suppressed by E-col but mildly enhanced by H2CO+ vibrational excitation. PT occurs by a direct mechanism at high energies, but appears to be mediated by reactantlike complexes at low energies. The other major low energy channel corresponds to H-2(+) transfer, and the majority of these product ions go on to eliminate CO, producing H2S+. Both H-2(+) transfer and H2S+ channels are strongly inhibited by E-col and vibrational excitation, which is interpreted in terms of competition with other channels. Charge transfer occurs in short time scale collisions at all energies, and is strongly enhanced by E-col and by vibrational excitation. The vibrational effects for all channels are mode specific.