Based on a redox kinetic mechanism, we derive a rate expression for NO oxidation over Cu-zeolite catalysts, and fit it to a set of NO oxidation experiments carried out over a commercial Cu-zeolite SCR catalyst with chabazite structure. The so developed model is able to predict the complex behavior of the NO oxidation reaction in good agreement with data covering the effects of NO, O-2, NO2 and H2O feed contents, GHSV and reaction temperature (150-350 degrees C). We show also that the dependency of the negative kinetic order of NO2 on the operating temperature is consistent with the proposed mechanism. Since NO oxidation in an NH3-SCR converter may affect the overall deNO(X) activity, the herein presented model is also relevant to characterize and describe the behavior of state-of-the-art SCR catalysts.