The present invention relates to a method of reducing the deposit of metallic transition metal, particularly palladium, on a metal part in hydrogenation reactions using hydrogen and a heterogenous supported palladium catalyst. These metallic transition metal deposit, particularly palladium deposits, are particularly formed at areas which are exposed to high velocity and shear forces of the hydrogenation mixture comprising the transition metal catalyst, particularly palladium catalyst. They are significantly reduced or even avoided when the surface of the respective metal parts are coated by a plasma sprayed ceramic coating.