NOVELTY - Device (8) forming electrical and fluidic interconnect to high temperature steam electrolysis reactor or solid oxide fuel cell, comprises five flat plates (82) elongated by two axes of symmetry orthogonal to each other with the two end plates (81) identical to each other and with two intermediate plates (83), arranged between each end plate and the central plate, identical to each other, one of end plates is in contact with plane of cathode of elementary adjacent electrochemical cell (C1) and other of end plates is in contact with plane of anode of elementary adjacent electrochemical cell.    USE - The electric and fluidic interconnector is useful in electrolytic reactor for fuel cell (all claimed).    ADVANTAGE - The electric and fluidic interconnectors: are inexpensive to produce; and have reduced with and thickness while retaining the good performance of the electrochemical cells.    DETAILED DESCRIPTION - Device (8) forming an electrical and fluidic interconnect to a high temperature steam electrolysis reactor or a solid oxide fuel cell, comprises five flat plates (82) elongated by two axes of symmetry orthogonal to each other with the two end plates (81) identical to each other and with two intermediate plates (83), arranged between each end plate and the central plate, identical to each other, one of the end plates is intended to come into mechanical contact with the plane of a cathode of a elementary adjacent electrochemical cell (C1) and the other of the end plates is intended to come into mechanical contact with the plane of an anode of a elementary adjacent electrochemical cell, where each of the elementary adjacent electrochemical cells, solid oxide fuel cell, is formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode of the device. Each of the five flat plates is pierced around its central portion, four lights, where the lights of the first to fourth plates, the first and second ports are arranged on either side of the X axis and on the same side with respect to the Y axis, while the third and fourth lights are disposed on either side of the X axis and on the same side respect to the Y axis, opposite to that in which are disposed the first and fourth lights and the first and fourth lights are arranged on either side of the Y axis and on the same side with respect to the X axis. The core sheet comprises undrilled central portion. Each of the two end plates have a central portion formed with many lumens, where the fifth ports of end plate, are elongated to a length substantially corresponding to the length of the portion according to a central X axis. Each of the two intermediate plates comprise two parts each pierced by an elongate slot over a length corresponding substantially to the length of the central portion along the other Y axis, and the two lights of each of the intermediate plates, the fifth and sixth intermediate plate lights, comprises sheets of tongues spaced apart from each other by forming a comb. The fifth lumen of one of the intermediate plates is in fluid communication with the first light of the intermediate tails and the sixth port of the intermediate plates is in fluid communication with the third light of the intermediate plates, while the fifth light from the other of the intermediate plates is in fluid communication with the second light from the other intermediate plates and the sixth lumen of the other of the intermediate plates is in fluid communication with the fourth light of the other intermediate plate, where the five plates are laminated and joined together such that each of the first to fourth ports of the five plates in fluid communication with the first to fourth ports of corresponding other four plates, respectively. The fifth and sixth of each light sheet means are in fluid communication with the fifth lights of one of the end plates and the tabs of each intermediate plate are supported against both the walls separating the fifth ports of one of the end plates and against the central portion not pierced with the core sheet. INDEPENDENT CLAIMS are also included for    (1) a reactor for electrolysis comprising a stack of elementary electrolytic cells, solid oxide fuel cell type, each of which is formed of a cathode, an anode and a electrolyte interposed between the cathode and the anode, and many electrical and fluidic interconnectors, each arranged between two adjacent elementary cells with one of the end plate in electrical contact with the cathode of one of the two elementary cells and the other of the end plate in electrical contact with the anode of other two elementary cells;    (2) operating an electrolytic reactor comprising feeding the first lights with water vapor simultaneously and fourth lights a draining gas (e.g. air), recovering hydrogen product by electrolysis of water vapor in the third lights, and simultaneously producing oxygen by electrolysis of water vapor in the second lights;    (3) solid oxide fuel cell comprising a stack of elementary electrochemical cells of solid oxide fuel cell type, each formed of a cathode, an anode and an electrolyte interposed between the cathode and the anode, and many of the electrical and fluidic interconnectors, each arranged between two adjacent elementary cells with one of the end plate in electrical contact with the cathode of one of the two elementary cells and the other of the end plate in electrical contact with the anode of other of the two elementary cells; and    (4) operating solid oxide fuel cell, comprising fed feeding with air to the first lights and the fourth lights, simultaneously, and recovering hydrogen produced in the third lights and hydrogen not used in second lights, simultaneously.    DESCRIPTION OF DRAWING(S) - The figure shows an exploded view of an interconnector showing the five flat plates constituting two electrolysis cells.    Elementary adjacent electrochemical cell (C1)    Electrical and fluidic interconnect device (8)    End plate (81)    Flat plate (82)    Intermediate plate (83)