Abstract: The invention relates to a machine for the surface processing of metal parts by immersion into at least one processing liquid contained in a processing tank comprising a plurality of tanks arranged in series and to a device for transferring the parts between the tanks, said tanks each including a rotary structure mounted on a rotation axis for receiving said parts submerged by a rotation movement of the rotary structures such that the air bubbles generated by the immersion of the parts are chased from the surfaces thereof, machine in which said rotation axis are rotatingly rigidly connected and driven by a common driving device. The tanks arranged in series may be contiguous and the rotation axes of the rotary structures may be aligned and assembled so as to form a common rotation axis extending through the entire machine.