Nitrous oxide (N2O) is one of the top three greenhouse gases, together with carbon dioxide and methane, but it is stable enough not to be easily decomposed under thermocatalytic conditions, even at high temperature (445 degrees C). Herein, an efficient N2O decomposition method is reported using nickel oxide catalyst under mechanochemical conditions operated near ambient temperature. The mechanochemical N2O decomposition method exhibited a rapid reaction rate of 1761.3 mL h-1 and a high conversion of 99.98% even at 42 degrees C, compared to the thermochemical method (294.9 mL h-1 and 49.16% at 445 degrees C). Unlike equilibrium thermocatalytic states, the non-equilibrium mechanocatalytic states induced by intensive dynamic mechanochemical actions are responsible for effective N2O decomposition under mild temperature conditions.