Decomposition of the toxic gas N2O over gold supported ZSM-5 zeolite has been investigated by using the M06-L functional. The activation energy for the Au/H-ZSM-5 is 15.2 kcal/mol lower than on the Au/ZSM-5, which is 26.7 kcal/mol. The results suggest that the Au/H-ZSM-5 zeolite is more active than Au/ZSM-5 zeolite. Our findings also indicate that the charge state of Au plays an important role for controlling N2O decomposition and the supported zeolite facilitates charge transfer between metal and N2O which is a key process for the reaction. (C) 2012 Elsevier B. V. All rights reserved.