The catalytic cycle of NO and NO2 (NOx) is known to be one of the mechanisms through which plasma enhances the ignition of hydrocarbons. To better understand the kinetics of NOx within a non-equilibrium plasma, the formation of NOx by repetitively pulsed dielectric-barrier discharges was studied experimentally and numerically. The experiments were carried out by applying highvoltage pulses on N2/O2/C2H4 mixtures highly diluted with Ar, flowing through a flow reactor at isothermal conditions. Numerical simulations were performed by a zero-dimensional plasma kinetics code, which combines CHEMKIN and a Boltzmann equation solver. The present work examines the kinetics at different temperatures and mixture compositions over a wide range of timescales. Even at low temperatures, the major NOx formation path is identified to be the one found in the Zel'dovich mechanism, namely N+O2→NO+O, owing to the production of N atoms by the plasma. The enhancement of the hydrocarbon oxidation by the NOx catalytic cycle is confirmed, and the products of the oxidation process are discussed in detail.