Assembly, characterised in that it comprises: - a stack having SOEC/SOFC-type solid oxides operating at a high temperature, - a furnace with which the stack is coupled for the supply and discharge of the gases, - a coupling system for the high-temperature sealed coupling of a stack having SOEC/SOFC-type solid oxides, for coupling the stack with the furnace, comprising: - a hollow connector that is at least partially threaded on the outer surface thereof, referred to as a threaded connector, intended to be attached to a gas inlet/outlet pipe, the threaded connector comprising an opening for establishing fluid communication with the gas inlet/outlet pipe, - a hollow connector having an outer surface that is at least partially smooth, referred to as a smooth connector, intended to be attached to a gas inlet/outlet pipe of the stack having SOEC/SOFC-type solid oxides, the smooth connector comprising an opening for establishing fluid communication with the gas inlet/outlet pipe of the stack, the smooth connector and the threaded connector each comprising an opening (44, 45) for establishing fluid communication with one another, - a threaded nut, capable of engaging with the threaded connector to form a screw/nut system and capable of sliding relative to the smooth connector, the threaded nut comprising, on the inner surface thereof, a first threaded portion engaging with the thread of the threaded connector and a second smooth portion in sliding contact with the smooth connector, on the smooth outer surface thereof. - a stack having SOEC/SOFC-type solid oxides operating at a high temperature, - a furnace with which the stack is coupled for the supply and discharge of the gases, - a coupling system for the high-temperature sealed coupling of a stack having SOEC/SOFC-type solid oxides, for coupling the stack with the furnace, comprising: - a hollow connector that is at least partially threaded on the outer surface thereof, referred to as a threaded connector, intended to be attached to a gas inlet/outlet pipe, the threaded connector comprising an opening for establishing fluid communication with the gas inlet/outlet pipe, - a hollow connector having an outer surface that is at least partially smooth, referred to as a smooth connector, intended to be attached to a gas inlet/outlet pipe of the stack having SOEC/SOFC-type solid oxides, the smooth connector comprising an opening for establishing fluid communication with the gas inlet/outlet pipe of the stack, the smooth connector and the threaded connector each comprising an opening (44, 45) for establishing fluid communication with one another, - a threaded nut, capable of engaging with the threaded connector to form a screw/nut system and capable of sliding relative to the smooth connector, the threaded nut comprising, on the inner surface thereof, a first threaded portion engaging with the thread of the threaded connector and a second smooth portion in sliding contact with the smooth connector, on the smooth outer surface thereof. - a hollow connector that is at least partially threaded on the outer surface thereof, referred to as a threaded connector, intended to be attached to a gas inlet/outlet pipe, the threaded connector comprising an opening for establishing fluid communication with the gas inlet/outlet pipe, - a hollow connector having an outer surface that is at least partially smooth, referred to as a smooth connector, intended to be attached to a gas inlet/outlet pipe of the stack having SOEC/SOFC-type solid oxides, the smooth connector comprising an opening for establishing fluid communication with the gas inlet/outlet pipe of the stack, the smooth connector and the threaded connector each comprising an opening (44, 45) for establishing fluid communication with one another, - a threaded nut, capable of engaging with the threaded connector to form a screw/nut system and capable of sliding relative to the smooth connector, the threaded nut comprising, on the inner surface thereof, a first threaded portion engaging with the thread of the threaded connector and a second smooth portion in sliding contact with the smooth connector, on the smooth outer surface thereof.