A high voltage power cable assembly for a power distribution system of a vehicle incorporating an integrated cooling system is presented. The power cable assembly comprises first and second electrical conductors spaced apart from one another and extending longitudinally. The power cable assembly further comprises a longitudinally extending cooling tube arranged between the first and second electrical conductors such that opposing portions of an external surface of the cooling tube are provided in direct contact with corresponding portions of the insulating material of the electrical conductors over a heat exchange region so as to transfer heat from the electrically conductive core of the electrical conductors to a coolant medium circulating in an internal channel of the cooling tube.