A device for producing water on board an aircraft includes at least one high temperature fuel cell entirely or partially integrated into a combustion chamber arrangement of a gas turbine aircraft engine. The combination of at least one fuel cell and a gas turbine engine is adapted to operate exclusively with hydrogen and atmospheric oxygen, and is embodied in an aircraft propulsion engine and/or an auxiliary power unit used for producing compressed air for a cabin and a power supply of the aircraft. The at least one high temperature fuel cell is fed with pure hydrogen on an anode side and with air on a cathode side. The combustion chambers of the turbine engine are fed with an air-hydrogen mixture, whereby at least the hydrogen supply can be regulated or completely shut off.