Abstract: In a casting mould and cooling unit for use in the continuous casting of molten metal, the layers of lubricious, non-wetting material such as graphite (12) bounding the solidification chamber (10) of the mould are secured to the copper cooling jacket walls (14) through the agency of interfitting ribs and grooves (18,20) and a layer (22) of bonding material so as to afford good thermal conduction between the layers (12) and walls (14) even if a gap develops at the interface. The interfitting ribs and grooves are so shaped that each wall (14) and the corresponding layer (12) can be assembled by bringing them together facewise on. At least some of the grooves (20) are of re-entrant form to provide a mechanical key so as to reduce the possibility of a gap developing at the interface.