Silver-modified H-MCM-41-50, H-Beta-11 and SiO2 catalysts were synthesized by incipient wet impregnation method using aqueous solution of silver nitrate. The catalysts were characterized using X-ray powder diffraction, scanning electron microscope, X-ray fluorescence, nitrogen physisorption and FTIR spectroscopy. The catalysts were tested in the heterogeneous catalytic decomposition of ozone at ambient temperature. The highest degree of ozone decomposition was observed over the mild acidic 5 wt.% Ag-H-MCM-41-50 (98%) mesoporous molecular sieve catalyst followed by 5 wt.% Ag-SiO2 (90%). It was found that the most acidic catalyst 5 wt.% Ag-H-Beta-11 showed the lowest ozone decomposition. The content of Ag was also observed to influence the ozone decomposition. The 5 wt.% Ag-H-MCM-41-50 mesoporous molecular sieve catalyst exhibited higher catalytic activity than 2 wt.% Ag-H-MCM-41-50. The acidic properties, structure of catalyst supports and the metal content were found to be important for the ozone decomposition reaction. (c) 2006 Elsevier B.V. All rights reserved.