Abstract: Using quantum-chemical methods we studied the possibility and mechanism the photochemical oxidation of epoxy olefins by nitro compounds. It was first found the structure of the corresponding transition state. Methods of DFT / 6-31g + (d) and DFT / 6-311 + g (d) was used to studied the reaction of sulfur oxides (II, IV) with nitro compounds in the ground and excited states. It was first made the assumption that in the course of the photochemical oxidation of various substrates by nitro compounds in excited states formed transition states containing nitrosooxide fragments. Experimentally and theoretically it was studied the oxidation of nitroso compounds by nitro compounds in the excited states. In the course of the reactions of nitrogen oxides and sulfur-containing compounds in the reactions of the photochemical oxidation of nitroso compounds by nitro compounds in the states of different multiplicity. By means of CASSCF we determined the opportunity of appearance of the singlet - triplet transition for nitroso oxides. It was shown the proximity of the S0 and T2 levels.