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In case of emergency associated with the emission of hydrogen in the oxidizing environment, the main danger is the uncontrolled explosive conversion of formed combustible gas mixture. It is believed that there are three main channels of the combustion reaction: to form HO2 +H, to form a water molecule H2O + O and to form a pair of hydroxyl radicals 2OH. At the moment, many of the studies on the subject use only channel forming HO2 + H products, making it the main channel of the chain reaction. The other two channels are discarded as they are considered inaccessible in terms of energy, and, thus, do not participate in the global process of combustion. The authors carried out numerical simulation of hydrogen combustion in oxygen using modern techniques and software tools. An algorithm based on the Hartree-Fock basis 6-311+G with an additional cycle of refinement calculations based on density functional theory with the hybrid functional PBE1PW91 was used. This algorithm allowed to calculate various characteristics of the reactants, products, and some transition states for all three channels initiating a chain reaction. These characteristics, as energy and geometric, coincide reasonably well with certain reliable experimental data, which shows the overall reliability of the obtained method. It was also shown that the transition state of the channel forming a pair of hydroxyl radicals 2OH is theoretically available in the terms of energy, and, thus, this channel should not be completely excluded from the global combustion process.