An apparatus for mounting a radiator (2) on a wall (1) includes an elongate, vertical rail (3) with a lower retainer device disposed at the lower end for carrying the radiator (2). At the upper end, the rail (3) has an upper retainer device for engagement with the radiator. The upper retainer device is reciprocally movable in relation to the lower and is spring pretensioned (14) towards it. The upper retainer device has a locking portion (16) for engagement with both the rail (3) and the radiator (2) and is disposed partly in an actuator portion (4) movable along the rail (3), the actuator portion transferring to the locking portion (16) the spring pretensioning (14). The locking portion (16) is, together with the actuator portion (4), movable towards the lower retainer device under the action of the spring pretensioning (14). On upward actuation of the radiator(2) towards the locking portion (16), this is disposed to enter into positionally fixing locking engagement with the rail (3).