Ground-level ozone causes great harm both to ecosystems and human health and should be strictly controlled. Manganese oxide (MnOx) is severely limited by catalyst deactivation due to environmental variations such as humidity and temperature. Herein, amorphous MnOx, prepared via a simple and mild redox reaction showed complete elimination of 40 ppm ozone at a high weight hourly space velocity of 600,000 mL.g(-1) h(-1), under the mild environmental condition with the relative humidity of 50 % and 25 ?C. It also kept predominant activity and remarkable stability even at harsh environmental conditions of low temperature (0 ?C) or high humidity (90 %). The superior ozone decomposition performance of MnOx resulted from the abundant grain boundaries and manganese redox pairs, which promoted oxygen vacancies generation and electron transfer. The findings may shed new light on the design of highly efficient and stable MnO(x )catalysts and are expected to drive great advances for large-scale practical applications.