Device, intended to form an individual unit of an electrolysis or co-electrolysis reactor, comprising: - an individual solid oxide (SOEC) electrolysis cell formed of a cathode, of an anode and of an electrolyte inserted between the cathode and the anode, - a first (5.1) and a second (5.2) electrical and fluid interconnector, each consisting of a component made of electron-conducting and gastight material; the first and second interconnectors being arranged on either side of the individual cell; the first interconnector (5.1) being pierced with a conduit for supplying steam, which opens at the periphery of one side of the cathode, and with a conduit for recovering the hydrogen produced, which opens at the periphery of the cell on the side of the cathode opposite the side on which the supply conduit opens, so as to distribute the steam supplied and the hydrogen produced, in a compartment; the second interconnector (5.2) being pierced with a conduit for recovering the oxygen produced, which opens at the periphery of the cell on the side of the anode so as to distribute the oxygen produced to the recovery conduit in a compartment; - a first electrical contact element, different from the interconnectors, which is in mechanical contact on the one hand with the first interconnector (5.1) and on the other hand with the cathode; the first electrical contact element being a porous substrate; characterized in that it comprises: - a first seal arranged at the periphery of the individual cell and bearing both against the first interconnector and against the second interconnector; - a second seal arranged at the periphery of the anode of the individual cell and bearing both against the second interconnector (5.2) and against the electrolyte; - a third seal, inserted in the porous substrate of the first contact element, the seal bearing against the first interconnector (5.1) and the cathode by being arranged at the periphery of the conduits for supplying steam and for recovering the hydrogen produced, respectively, thus delimiting the compartment for distributing the steam supplied and the hydrogen produced. - an individual solid oxide (SOEC) electrolysis cell formed of a cathode, of an anode and of an electrolyte inserted between the cathode and the anode, - a first (5.1) and a second (5.2) electrical and fluid interconnector, each consisting of a component made of electron-conducting and gastight material; the first and second interconnectors being arranged on either side of the individual cell; the first interconnector (5.1) being pierced with a conduit for supplying steam, which opens at the periphery of one side of the cathode, and with a conduit for recovering the hydrogen produced, which opens at the periphery of the cell on the side of the cathode opposite the side on which the supply conduit opens, so as to distribute the steam supplied and the hydrogen produced, in a compartment; the second interconnector (5.2) being pierced with a conduit for recovering the oxygen produced, which opens at the periphery of the cell on the side of the anode so as to distribute the oxygen produced to the recovery conduit in a compartment; - a first electrical contact element, different from the interconnectors, which is in mechanical contact on the one hand with the first interconnector (5.1) and on the other hand with the cathode; the first electrical contact element being a porous substrate; characterized in that it comprises: - a first seal arranged at the periphery of the individual cell and bearing both against the first interconnector and against the second interconnector; - a second seal arranged at the periphery of the anode of the individual cell and bearing both against the second interconnector (5.2) and against the electrolyte; - a third seal, inserted in the porous substrate of the first contact element, the seal bearing against the first interconnector (5.1) and the cathode by being arranged at the periphery of the conduits for supplying steam and for recovering the hydrogen produced, respectively, thus delimiting the compartment for distributing the steam supplied and the hydrogen produced. - a first seal arranged at the periphery of the individual cell and bearing both against the first interconnector and against the second interconnector; - a second seal arranged at the periphery of the anode of the individual cell and bearing both against the second interconnector (5.2) and against the electrolyte; - a third seal, inserted in the porous substrate of the first contact element, the seal bearing against the first interconnector (5.1) and the cathode by being arranged at the periphery of the conduits for supplying steam and for recovering the hydrogen produced, respectively, thus delimiting the compartment for distributing the steam supplied and the hydrogen produced.