Temperature-programmed desorption of NO (TPD) and temperature-programmed reduction of NO by propene and ethanol (TPSR) over the catalyst with redox properties and the structure of spinels -Co3O4 and CoFe2O4 - were investigated. The TPD experiments can determine the temperature range in which the deNO(x) proceeds and provide information about the heat of adsorption of NO on the surface of catalysts. The values of the adsorption heat are much higher in the case of the catalyst with weaker redox properties (CoFe2O4), because of stronger bonds between the adsorbate and the surface of catalyst. The TPD and TPSR experiments show that ethyl alcohol is a more active reductant in the deNOx process than propene. The maximum of NOx conversion is higher with ethyl alcohol used as a reductant in both cases of investigated catalysts. Moreover, the temperature of the maximum degree of NOx reduction is lower in the case of alcohol used as an reductant. Co3O4 is a more active and suitable catalyst for the deNOx process than CoFe2O4. (C) 2010 Elsevier B.V. All rights reserved.