Mesoporous molecular sieve Na-MCM-41 with Si/Al ratio 20 and 50 and Na-beta zeolite with Si/Al ratio 11 were synthesized and characterized using X-ray powder diffraction, scanning electron microscope and nitrogen adsorption. The Ag ( 5 and 2 wt%) modi. cations of H-MCM-41-20, H-MCM-41-50 and H-beta-11 catalysts were carried out using impregnation method. The catalysts were tested in the decomposition of ozone at ambient temperature. The 5 wt% Ag-H-MCM-41 catalyst showed a very high decomposition of ozone (similar to98%). The 5 wt% Ag-H-MCM-41-50 catalyst exhibited higher decomposition rate than 2 wt% Ag-H-MCM-41-50. The Ag modified H-MCM-41 catalyst with higher Si/Al ratio showed higher reaction rate than the catalyst with lower Si/Al ratio. The H-MCM-41 catalyst without Ag exhibited the lowest decomposition of ozone indicating an important role of Ag in the reaction.