Abstract: This invention concerns a transformer radiator. The radiator includes an inlet manifold, an outlet manifold and a heat exchange fin. The find extends between and is connected to the inlet and outlet manifolds. The heat exchange fin defines at least one oil flow passage to convey transformer oil, which, in use, enters the radiator through the inlet manifold, to the outlet manifold. The heat exchange fin is further provided by a single component having a continuously undulating profile and the manifolds extend transversely to the turns of the undulating profile.