Ce-Ni-O catalysts of different Ni content prepared by co-precipitation and impregnation methods have been characterized by XRD, XPS and surface potential technique and tested in oxidative dehydrogenation of propane (ODH). The systems have been found to be active and selective already at low relatively temperatures similar to300degreesC: for the CeNi1 precipitated catalyst (nNi/nCe (bulk) = 1), the yield of propene amounted to 11% with the selectivity of about 60%. The effect of the potassium addition to the impregnated samples was also studied. This addition to the Ni/Ce impregnated sample led to the increase in the selectivity to propene but to the decrease in conversion. From the characterization of the catalysts, it was concluded: at low Ni loadings, the ceria surface is gradually covered with the dispersed NiOx species with higher surface potential values than that of ceria. These species are considered to be active in the ODH of propane. At higher loadings (Ni/Ce > 0.2) other species (most probably crystalline NiO), not active in the catalytic reaction are formed. (C) 2002 Elsevier Science B.V. All rights reserved.