The invention relates to a valve assembly, comprising a valve (4) which is associated with a gas conduit (8), has a valve disc (6) and a valve stem (7) supporting said valve disc and is provided with a cooling device. In said valve assembly, a simple design, high functional reliability and a good energy balance can be achieved by using a gaseous cooling medium or a cooling medium which consists at least partially of components that can be converted into a gaseous state. The cooling medium is discharged as gas into a gas conduit (8) via at least one outlet chamber (17), and for this purpose each discharge duct (19) originating from the outlet chamber (17) opens into a gas conduit (8).