A series of different amount ZrO(2)-promoted SiO(2) supported Ni catalysts were prepared and used for methane autothermal reforming with CO(2) and O(2) [MATR] to synthesis gas in a fluidized bed reactor. Pulse-injected surface reactions and in situ XRD characterizations disclosed that CO(2) dissociated exclusively at the boundary between Ni and ZrO(2). O species derived from CO(2) dissociation overflowed to metallic Ni and accelerated the activation of methane. Ni/5ZrO(2)-SiO(2) catalyst with larger Ni-ZrO(2) boundary exhibited the best activity and stability for MATR even at an extremely space velocity 90,000 h(-1). (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.