The surface structure and catalytic properties of a mixed phase of copper and cobalt oxides supported on magnesium fluoride and alumina have been studied. The surface properties have been characterised by low temperature adsorption of nitrogen, XRD and TPR-H-2. Catalytic activity of the catalysts have been examined in CO oxidation and NO reduction by propene. The oxides studied react with each other to spinels: CuCo2O4 after calcination at 400 or 550 degrees C and CoAl2O4 after treatment at 950 degrees C. The spinels have different effect on catalytic activity. In CO oxidation, the spinels are more effective than monoxide phases, however, in NO reduction by propene the copper oxide supported on MgF2 is the most active. (c) 2005 Elsevier B.V. All rights reserved.