Recently, N2O emission from fossil fuel combustion has become a focus of attention since N2O is not only a greenhouse gas but also an agent of ozone destruction in the stratosphere. The calcium oxide(CaO) is known to be a catalyst of N2O decomposition. This study was carried out N2O decomposition over calcium oxide by use of a fixed bed reactor. It was found that N2O decomposition increased with increasing temperature. The result of kinetic study gained the heterogeneous reaction rate on N2O decomposition. Reaction rate is -r=1.646 × 10(15)Exp(-235000/RT)KN2OCN2O/1 + KN2OCN2O.