In the present study, systematic chemical kinetic calculations were made to investigate the promotion of NO-NO2 conversion due to the addition of various hydrocarbons (methane, ethylene, ethane, propene, propane) in the nonthermal plasma treatment. It is included in the present conclusion that the reaction between the added hydrocarbon and oxygen radical induced by electron collision due to nonthermal plasma discharge, can be considered as a primary process for triggering the overall NO oxidation. Upon the completion of the initiating step, various radicals (OH, HO2 etc.) successively produced by hydrocarbon decomposition lead to the eventual NO-NO2 conversion. With the initiating step less activated, hydrocarbon consumption rate becomes very low, thereby the targeted level of NO conversion can only be achieved by the addition of more input energy. Present study showed, among 5 hydrocarbons simulated, ethylene and propene to have higher affinity with O radical under all conditions, hence very fast and efficient NO-NO2 oxidation is possible. It was also shown that propene is superior to ethylene in the aspect of NOx removal.