We have observed significant enhancements in the rate and capacity of NO2 uptake caused by the injection of ozone over the zeolite H-ZSM-5, which has a high SiO2/Al2O3 ratio. We performed these experiments using a gas-flow system in which the profiles of NO2 adsorption and subsequent temperature-programmed desorption were measured by Fourier transform infrared spectroscopy. We interpret these results in two ways: either by assuming that fast surface reactions lead to N2O5 formation or by considering that ozone suppresses the blockage of the reactive Bronsted-acidic protons.