NOVELTY - The water electrolysis device comprises a stack of elementary electrolytic cells (C1, C2, C3 up to Cn) formed of a cathode (2), an anode and an electrolyte (6) interposed between the cathode and anode, and a first device (8) forming an electrical and fluid interconnector consisting of a metal part (80) delimited by plane P1. The first metal part comprises chamber (801) and holes (800) distributed over the surface perpendicular to the plane and opening in the plane P1 and the chamber. The plane P1 of the first interconnector is in mechanical contact with a plane of the cathode.    USE - The device is useful for electrolysis of water at high temperature and in an assembly for the production of hydrogen (claimed).    ADVANTAGE - The device provides is capable of easily and economically producing the hydrogen with high efficiency by enhancing the electrolysis of water at high temperatures in real time, and provides uniform current density in each electrolysis cell and increases the rate of steam used by each electrolysis cell.    DETAILED DESCRIPTION - The water electrolysis device comprises a stack of elementary electrolytic cells (C1, C2, C3 up to Cn) formed of a cathode (2), an anode and an electrolyte (6) interposed between the cathode and anode, and a first device (8) forming an electrical and fluid interconnector consisting of a metal part (80) delimited by plane P1. The first metal part comprises a chamber (801) and holes (800) distributed over the surface perpendicular to the plane and opening in the plane P1 and the chamber. The plane P1 of the first interconnector is in mechanical contact with a plane of the cathode. A ratio between the surface of the holes and the surface P1 plane is less than 10%. The number and/or size of holes and/or their distribution is determined to control the losses of fluid flowing in the cathode contacting with the plane P1 of the first interconnector. A second device forming an electrical and fluid interconnector is arranged in the device, and comprises a metal part defined by plane P2. The second metal part comprises a chamber and holes distributed over the surface perpendicular to the plane and opening in the plane P2 and the chamber. The plane P2 of the second interconnector is in mechanical contact with the plane of the anode. The interconnecting plate consists of three metal plates assembled together at their periphery. The first and second plates comprise holes spread over the surface perpendicular to their thickness and opening on its two flat faces. The third plate comprises a groove opening to one of faces of the first plate next to the holes and a groove opening to one side of the second opening. A space is defined between each groove and the first and second plates constituting one of two chambers. A clamping unit is adapted to provide a given contact force between the two plates on both sides of the stack of cells. A first joint is arranged at the periphery of the anode of one cell and in direct mechanical contact with electrolyte of the cell and the second interconnector. The water electrolysis device further comprises a sealed envelope to contain steam pressure, a first fluid connection opening inside the sealed envelope to feed with steam under pressure, a second fluid connection connected to the chamber of the first interconnector and opening to the outside of the sealed envelope for collecting and evacuating the hydrogen produced at the cathode, and a third fluid connection connected to the chamber of the second interconnector and opening to the outside of the sealed envelope for collecting and evacuating the oxygen produced at the anode. The thickness on the periphery of the cathode is in direct contact with the interior of the sealed envelope. A second fluid connection comprising a channel is arranged for collection and evacuating hydrogen produced at the cathode of a cell made in the metal part of the first interconnecter arranged at a distance from the cell. The two channels for collection and evacuating hydrogen produced at the cathode of two adjacent elementary cells are opposite to each other. The two channels are separated from each other by a first holed spacer, a second joint in direct mechanical contact with the first holed spacer and with the first interconnecter of one of two elementary cells and a third joint in direct mechanical contact with the first holed spacer and with the second interconnecter of the other two elementary cells. The height of the first holed spacer and the second and third compressed joint is equal to the thickness of an electrolytic cell. The third fluid connection comprises a channel for collecting and evacuating oxygen produced at the anode of a cell produced in the metal part of the second interconnector arranged at a distance from the cell. The two channels are further separated from each other by a second holed spacer, a fourth joint in direct mechanical contact with the second holed spacer and the first interconnector of one of two elementary cells and fifth joint in direct mechanical contact with the second spacer and the second interconnector. The height of the second spacer and the fourth and fifth compressed joint is equal to the thickness of an electrolysis cell. The first, second, third, fourth and fifth sealed joints are metallic. A section of electrolysis cell is circular.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic sectional view of a water electrolysis device.    Cathode (2)    Electrolyte (6)    First device (8)    Metal part of the first device (80)    Holes (800)    Chamber of the first device. (801)