Partial oxidations of CH4, C2H6, C3H8, and iso-C4H10 with O-2 were promoted by addition of NO in the gas phase. The addition of NO increased the conversion rate of alkanes and decreased the initiation temperatures for the reactions. Moreover, selectivities and yields to oxygenates, aldehydes, ketones and alcohols, were remarkably improved by the addition of NO. The maxima of one-pass yields of oxygenates were 7% for CH4, 11% for C2H6, 13% for C3H8, and 29% for iso-C4H10. It is suggested that NO2 produced from NO and O-2 is the initiator for the oxidation of light alkanes. Alkyl nitrite was proposed as the reaction intermediate for the formation of oxygenates. The alkyl nitrite decomposes into oxygenates and NO that works as catalyst for the activation of O-2 and the oxidation of alkanes.