The character of the central hydrogen has been analysed in the [CH3-H-CH3]+ system, both at the absolute symmetric minimum, and at the stationary points of the reduced potential energy surface defined by imposing dC-C = 3 Å. For that purpose, ab initio calculations have been performed at the SCF-MO level using several common basis sets. For each geometry of chemical interest, the molecular orbitals arising from an ab initio Hartree-Fock wave function have been localized. The molecular orbital wave function has then been projected onto a set of valence bond structures describing the various hydride-transfer mechanisms. The ratio of hydride transfer to electron + hydrogen transfer has been assessed. © 1992.