NOVELTY - The sealing joint interposed between first and second elements (4', 6) respectively produced from materials having different thermal dilation coefficients, comprises first and second metallic contact portions spaced from one another according to axial direction (8) of a stack, a sealable connection unit (14) between the first and second metallic contact portions undergoing a relative displacement between them according to a radial direction (20) of the joint, and first and second sliding pieces stacked according to the axial direction.    USE - The sealing joint is useful in an assembly of an electrochemical cell system such as a high temperature electrolyzer or fuel cell (all claimed).    ADVANTAGE - The joint provides enhanced and precise sealing between an assembly of first and second elements in the electrochemical cell system thus preventing the escape of gas outside the electrolyzer or fuel cell and the recombination of hydrogen and oxygen and improving the performance and life of the fuel cell.    DETAILED DESCRIPTION - The sealing joint interposed between first and second elements (4', 6) respectively produced from materials having different thermal dilation coefficients, comprises first and second metallic contact portions spaced from one another according to axial direction (8) of a stack, a sealable connection unit (14) between the first and second metallic contact portions undergoing a relative displacement between them according to a radial direction (20) of the joint, and first and second sliding pieces stacked according to the axial direction and respectively coupled in rotation according to the radial direction of the first and second metallic portions. The first and second metallic contact portions are sealably contacted with respective first and second elements. The first and second sliding pieces are in contact with each other. The first and second metallic portions have a sealed contact member projecting in the axial direction of the stack towards outside of the joint, and a coupling member protruding in translation in the axial direction of the stack towards inside of the joint housed in an additional hole formed in its associated sliding direction. The sealable connection unit is produced from the same material of the metallic portions. Ratio of thickness of the first sliding piece and the thickness of the first metallic portion is 5, and ratio of thickness of the second sliding piece and the thickness of the second metallic portion is 2-5.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a sealing joint.    First and second elements (4', 6)    Axial direction of the stack (8)    Sealing joint (10)    Sealable connection unit (14)    Radial direction (20)    Axial force. (27)