Alumina Supported catalysts comprised of a ceria-zirconia solid solution and lanthanum nickelate promoted by Pt were tested in the partial oxidation of methane into synthesis gas under conditions (high temperature, short contact time, highly diluted gas mixture, small catalyst grains) providing acquisition of a catalyst intrinsic activity. The phase composition and reducibility of catalysts were characterized with XRD and TPR. The influence of the catalyst chemical composition, type of redox pretreatment and support phase composition on the activity has been studied. Prolonged relaxations of catalytic activity have been observed, and their nature is discussed taking into account the catalyst properties. (C) 2004 Elsevier B.V. All rights reserved.