Abstract: A cathode assembly for an electrolytic cell including a cathode block having a second surface and a first surface. The cathode block also including at least one sealing groove opening onto its first surface and a plurality of electrical contact plugs mounted in electrical contact with the first surface of the cathode block. The cathode assembly includes at least one current supply plate in electrical contact with at least one electrical contact plug, and is connected to at least one unit for connection to an electric current source. The cathode assembly includes at least one current supply bar having a coefficient of thermal expansion substantially identical to the coefficient of thermal expansion of the current supply plate and is sealed within the at least one sealing groove while being fastened to at least one current supply plate.