New reaction steps have been found for the gas phase system containing nitromethane and hydrogen sulphide molecules using the PBE/6-311++G** method. In combination with our previous results the obtained data allow us to propose the reaction mechanism as a set of the events such as the hydrogen transfer from the sulphur atom to the nitrocompound accompanied with formation of the hydrogenated nitromethane radical; and the singlet nitromethane regeneration by hydrogenated nitromethane radical reaction with the hydroxyl containing fragment. The mechanism leads to formation of the atomic sulphur and nitrosomethane as main products of the reaction. It was also predicted that the fluorescence at wavelength of 349 nm could be observed as result of the considered sulphanol and nitromethane interaction.