The oxidation of light hydrocarbons with different structure as well as oxidation of their mixtures by O-2 or NO over the Ag catalyst have been studied using the microcatalytic method in the non-steady-state regime. It was established, that the relative reactivity and adsorptive capacity of the hydrocarbons can be arranged in the next order: C2H2 > C5H10 > iso-C4H8 > n-C4H8 > C3H6 > C2H4 > n-C5H12, C3H8. The order of hydrocarbons reactivity in the complete oxidation is similar for molecular oxygen and nitric monoxide. However, the oxidation potential of NO is less than that of molecular oxygen. It was shown that there is the correlation between a relative constant for an olefin oxidability, its ionization potential, and a constant of the interaction rate of the olefin with atomic oxygen.