Spacer for an electrolyzer cell of substantially annular shape and comprising: a peripheral part having two parallel principal faces (105, 107) opposite each other, the distance separating the two principal faces (105, 107) defining a thickness of the spacer, and an internal part having a thickness strictly less than the thickness of the spacer, the peripheral part and the internal part being in one piece and connected to each other forming an internal annular shoulder so that the internal part has a substantially annular intermediate face extending in a plane parallel to the two principal faces (105, 107) of the peripheral part and situated between the two principal faces (105, 107), characterized in that: the spacer comprises a metal core and an electrically insulative envelope covering the core at least over the areas of the spacer in contact with an internal space of the electrolyzer cell in the assembled state, at least one groove is formed in the core, extending substantially along the circumference of the spacer, and in at least one of the two principal faces (105, 107) and the intermediate face, the at least one groove forming a housing for a sealing line (205, 207, 209) in the assembled state of the spacer, and the envelope includes at least one rib, extending substantially along the circumference of the spacer, and, in the rest state of the spacer, protruding from at least one of the two principal faces (105, 107) and the intermediate face, the at least one rib forming a sealing line (205, 207, 209) in the assembled state of the spacer, each rib being received in part in a corresponding groove. a peripheral part having two parallel principal faces (105, 107) opposite each other, the distance separating the two principal faces (105, 107) defining a thickness of the spacer, and an internal part having a thickness strictly less than the thickness of the spacer, the peripheral part and the internal part being in one piece and connected to each other forming an internal annular shoulder so that the internal part has a substantially annular intermediate face extending in a plane parallel to the two principal faces (105, 107) of the peripheral part and situated between the two principal faces (105, 107), characterized in that: the spacer comprises a metal core and an electrically insulative envelope covering the core at least over the areas of the spacer in contact with an internal space of the electrolyzer cell in the assembled state, at least one groove is formed in the core, extending substantially along the circumference of the spacer, and in at least one of the two principal faces (105, 107) and the intermediate face, the at least one groove forming a housing for a sealing line (205, 207, 209) in the assembled state of the spacer, and the envelope includes at least one rib, extending substantially along the circumference of the spacer, and, in the rest state of the spacer, protruding from at least one of the two principal faces (105, 107) and the intermediate face, the at least one rib forming a sealing line (205, 207, 209) in the assembled state of the spacer, each rib being received in part in a corresponding groove. the spacer comprises a metal core and an electrically insulative envelope covering the core at least over the areas of the spacer in contact with an internal space of the electrolyzer cell in the assembled state, at least one groove is formed in the core, extending substantially along the circumference of the spacer, and in at least one of the two principal faces (105, 107) and the intermediate face, the at least one groove forming a housing for a sealing line (205, 207, 209) in the assembled state of the spacer, and the envelope includes at least one rib, extending substantially along the circumference of the spacer, and, in the rest state of the spacer, protruding from at least one of the two principal faces (105, 107) and the intermediate face, the at least one rib forming a sealing line (205, 207, 209) in the assembled state of the spacer, each rib being received in part in a corresponding groove.