The reduction behavior of gold supported catalysts on mesoporous titania and zirconia was studied. The TPR, ESR, HRTEM and XPS methods were applied for the characterization of the state and structure of the catalysts. It was established that the nature of support plays a decisive role in the reactivity of the catalysts, in particular in their redox properties. The mesoporous nanostructured materials used in this study as supports for gold nanoparticles show very different behavior under hydrogen treatment. The ability of nanostructured zirconia to create F-centers leads to different charging of the supports surface, e.g. the supported gold nanoparticles which is the main reason for the observed differences between the both studied gold supported catalysts on mesoporous titania and zirconia. (c) 2005 Elsevier B.V. All rights reserved.