Following the recent finding [M. Kotobuki, R. Leppelt, D. Hansgen, D. Widmann, RJ. Behm, J. Catal. 264 (2009) 671 of a stable oxygen species on non-porous Au/TiO2 catalysts (TiO2: P25, Degussa), which is active for CO oxidation and which can be reversibly deposited and removed by exposure to O-2 and CO pulses, respectively, we here present results of a TAP (temporal analysis of products) reactor study on the oxygen storage capacity ('OSC') for three Au/TiO2 catalysts supported on mesoporous TiO2 with different structural characteristics and its relation to the CO oxidation activity. The results are compared with the corresponding behavior of the non-porous Au/P25 supported catalyst. While the general reaction behavior of all catalysts is similar, there are distinct differences both in the absolute oxygen storage capacity and in its relation to the catalytic activity, depending on the nature of the support. The differences are associated with variations in the structure of the Au/TiO2 interface and its perimeter, which is proposed as the adsorption site for active oxygen storage. (C) 2009 Elsevier Inc. All rights reserved.