Method for the catalytic decomposition of N2O

A reactor for the catalytic oxidation of ammonia to form nitrogen oxides which has a noble metal gauze catalyst and a heat exchanger in that order in the direction of flow, a catalyst for the decomposition of N2O is located between the noble metal gauze catalyst and the heat exchanger and in a process for the catalytic decomposition of N2O in a gas mixture obtained in the preparation of nitric acid by catalytic oxidation of ammonia, where the N2O is decomposed catalytically over a catalyst of the decomposition of N2O, the hot gas mixture obtained from the catalytic oxidation of ammonia is brought to contact with the catalyst for the decomposition of N2O prior to subsequent cooling.