Nitro compounds in the triplet state are strong oxidizing agents, one of the reactions of which is the excited-state hydrogen atom transfer. The energy characteristics of the reaction of triplet nitromethane with methylamine are obtained using ab-initio methods. MP2 and CASSCF methods were used. Calculated atomic charges has shown that the transfer of a proton must be accompanied by a simultaneous transfer of an electron. Optimization of the reaction complexes showed that in the course of the reaction there is a change in the reaction coordinate. The first stage is a rotation of methylamine molecule and the second stage is a lengthening of the C-H bond. Energetic and geometric parameters calculated by the MP2 and CASSCF methods are very close to each other which means the possibility of using the MP2 method for modeling similar processes as the main one.