A device and method for the decomposition of laughing gas including a gas inlet for supplying a laughing-gas-bearing gas; a first heat-exchanger for the exchange of heat between an exhaust and the laughing-gas-bearing gas; a heating device for occasional heating of the laughing-gas-bearing gas and a fixed-bed reactor in which a catalyst is included in order to decompose the laughing gas. The device also includes a gas outlet, through which exhaust leaving the fixed-bed reactor can be taken away through the heat exchanger. The device may be used to implement a method where the catalyst for decomposition of laughing gas is maintained at temperatures below 800° C. and in which the fixed-bed reactor is arranged as an adiabatic reactor.