The invention is concerned with a device of destroying ozone in gases by employing a recuperative plate heat exchanger (1) and an integrated electrical heating element (19, 21). The recuperative plate heat exchanger (1) is equipped with at least two planes, a preheating plane (11) and a recooling plane (13), whereby the flow direction of the gas treated in the recooling plane (13) is reversed relative to the ozone-containing gas in the preheating plane (11). Preferably, the flow directions of the preheating plane (11) and the recooling plane (13) cross over. The electrical heating element (19, 21) is situated in a reaction chamber (3) and heats up the ozone-containing gas preheated in the heat-exchanger up to temperatures of 350.degree. C. or more, and thus destroys the ozone within the gas almost to completion. The plate heat exchanger (1) works almost without pressure losses.