The present invention relates to stabilising compositions, particularly stabilising compositions which can be used to stabilise insulation or semi-conductive compositions, such as are used for electrically insulating wires and cables. The stabilising composition comprises: a first stabilising component comprising at least one fully hindered phenolic antioxidant; a second stabilising component comprising at least one partially hindered phenolic antioxidant; and a third stabilising component comprising at least one sulphur-containing antioxidant.