The MgF2-MgO system with different compositions is tested as a potential support of nickel oxide catalysts in the NO + C3H6 + O-2 reaction as a function of the MgF2/MgO ratio in the support and the reaction conditions. The study was performed at temperatures ranging from 250 to 475 degrees C in the reducing, oxidizing and stoichiometric conditions. The activity of NiO/MgF2-MgO catalysts was compared to those of NiO/MgF2, NiO/MgO, NiO/Al2O3 and NiO/SiO2. The highest activities were obtained for the catalysts supported on pure MgF2, especially in the reducing conditions. Mixed system MgF2-MgO gave a support on which nickel revealed much higher activities in NO reduction both in reducing and in oxidizing conditions when compared to NiO/MgO catalyst. (c) 2012 Elsevier B.V. All rights reserved.