An apparatus for electrophoretic repainting of metal objects, in particular lids for containers for food use, comprising: a tank containing an electrophoretic bath; an electrode, immersed in the electrophoretic bath; a conveyor line, provided with support elements for lids, the conveyor line being arranged such as to transit internally of the tank in order to immerse the lids in the electrophoretic bath; a unit for establishing an electrical contact with the lids transiting immersed in the bath, having an opposite polarity with respect to a polarity of the electrode immersed in the bath, in which the contact unit includes a rotation element,rotatable about a longitudinal axis thereof, parallel to the advancement direction of the conveyor line when transiting in immersion in the tank, an external lateral surface of the rotation element affording a groove, having a helical progression, destined to receive electrical conductor means such as to contact at least an end portion of the lids, the arrangement of the rotation element above the tank and with respect to the conveyor line being such that at least a point of the electrical conductor means maintains contact with the end portion of the lids during transit thereof in immersion in the bath of the tank; characterized in that the said support elements are such as to retain the lids, enabling the lids to advance along the conveyor line but without any constriction, so that the lids are freely retained by the support elements of the conveyor line, the contact between at least a point of the profiles of the electrical means and the end portion allowing the lids to be rotated with respect to the support elements, in consequence of the rotation of the rotation element. a tank containing an electrophoretic bath; an electrode, immersed in the electrophoretic bath; a conveyor line, provided with support elements for lids, the conveyor line being arranged such as to transit internally of the tank in order to immerse the lids in the electrophoretic bath; a unit for establishing an electrical contact with the lids transiting immersed in the bath, having an opposite polarity with respect to a polarity of the electrode immersed in the bath, in which the contact unit includes a rotation element,rotatable about a longitudinal axis thereof, parallel to the advancement direction of the conveyor line when transiting in immersion in the tank, an external lateral surface of the rotation element affording a groove, having a helical progression, destined to receive electrical conductor means such as to contact at least an end portion of the lids, the arrangement of the rotation element above the tank and with respect to the conveyor line being such that at least a point of the electrical conductor means maintains contact with the end portion of the lids during transit thereof in immersion in the bath of the tank; characterized in that the said support elements are such as to retain the lids, enabling the lids to advance along the conveyor line but without any constriction, so that the lids are freely retained by the support elements of the conveyor line, the contact between at least a point of the profiles of the electrical means and the end portion allowing the lids to be rotated with respect to the support elements, in consequence of the rotation of the rotation element.