An aircraft comprising a structure comprising a leakproof tank delimited by walls, of which at least one is in contact with the air outside the aircraft, and filled partly with a two-phase heat-transfer fluid, a fuel cell that is passed through by a heat-transfer fluid, and a line which takes the heat-transfer fluid at an output of the fuel cell and which reintroduces this heat-transfer fluid at an input of the fuel cell. The line passes through the leakproof tank immersed in the heat-transfer fluid in liquid phase.