A device for maintaining an electrochemical cell under current and at an operating temperature at least equal to 450°C during an analysis, by diffraction of an X-ray beam, of a first electrode of the cell, the cell including a solid electrolyte interposed between said first electrode and a second electrode of the cell, said device comprising: - a first and a second interconnector made of an electrically conductive material, the first interconnector having a contact face intended to be in contact with the first electrode and being configured to enable circulation and gas exchange between the first interconnector and the first electrode, as well as a passage of an X-ray beam to the first electrode, the second interconnector having a contact face intended to be in contact with the second electrode and being configured to allow circulation and gas exchange between the second interconnector and the second electrode; and - means (8, 9) for supplying current to the first and second interconnectors; the device being characterised in that it further comprises: - a thermal and atmospheric confinement chamber which comprises a body defining an internal cavity for housing a stack formed of the electrochemical cell sandwiched between the first and second interconnectors and which comprises a cover configured to close the cavity, said cover being provided with a window allowing X-rays to pass through, the first interconnector being intended to be disposed facing the cover so that X-rays passing through the window of the cover pass through the first interconnector to reach the first electrode; - means for supplying the chamber with a reactive gas; - means for evacuating at least one gas from the chamber; and - means for heating the cell and/or the reactive gas in the chamber to an operating temperature of the electrochemical cell, this operating temperature being at least equal to 450°C; wherein the contact face of the first interconnector is an openwork element whose openwork parts are arranged homogeneously, form from 30% to 80% of the surface of the openwork element and are disposed so as to obtain a homogeneous and symmetrical distribution of the reactive gas on the electrochemical cell, the openwork element being a grid; wherein the contact face of the second interconnector is a grooved element, for example a ribbed projection, adapted for distribution and/or collection of a gas. - a first and a second interconnector made of an electrically conductive material, the first interconnector having a contact face intended to be in contact with the first electrode and being configured to enable circulation and gas exchange between the first interconnector and the first electrode, as well as a passage of an X-ray beam to the first electrode, the second interconnector having a contact face intended to be in contact with the second electrode and being configured to allow circulation and gas exchange between the second interconnector and the second electrode; and - means (8, 9) for supplying current to the first and second interconnectors; the device being characterised in that it further comprises: - a thermal and atmospheric confinement chamber which comprises a body defining an internal cavity for housing a stack formed of the electrochemical cell sandwiched between the first and second interconnectors and which comprises a cover configured to close the cavity, said cover being provided with a window allowing X-rays to pass through, the first interconnector being intended to be disposed facing the cover so that X-rays passing through the window of the cover pass through the first interconnector to reach the first electrode; - means for supplying the chamber with a reactive gas; - means for evacuating at least one gas from the chamber; and - means for heating the cell and/or the reactive gas in the chamber to an operating temperature of the electrochemical cell, this operating temperature being at least equal to 450°C; - a thermal and atmospheric confinement chamber which comprises a body defining an internal cavity for housing a stack formed of the electrochemical cell sandwiched between the first and second interconnectors and which comprises a cover configured to close the cavity, said cover being provided with a window allowing X-rays to pass through, the first interconnector being intended to be disposed facing the cover so that X-rays passing through the window of the cover pass through the first interconnector to reach the first electrode; - means for supplying the chamber with a reactive gas; - means for evacuating at least one gas from the chamber; and - means for heating the cell and/or the reactive gas in the chamber to an operating temperature of the electrochemical cell, this operating temperature being at least equal to 450°C; wherein the contact face of the first interconnector is an openwork element whose openwork parts are arranged homogeneously, form from 30% to 80% of the surface of the openwork element and are disposed so as to obtain a homogeneous and symmetrical distribution of the reactive gas on the electrochemical cell, the openwork element being a grid; wherein the contact face of the second interconnector is a grooved element, for example a ribbed projection, adapted for distribution and/or collection of a gas.