A device for cooling hot gas to be discharged from an aircraft includes a duct for leading the hot gas from a hot gas source which is connectable to the device to an outlet point, and a frame which surrounds the duct and serves for mounting the duct. The duct is formed from one or more pipe sections and has one or more cooling air inlet points which is connectable to one or more cooling air sources in order to mix the hot gas with cooling air. An outlet pipe section of the duct extends outwards beyond the aircraft outer skin to lead hot gas through and out of a flow boundary layer on the outer skin.
