Pumice-supported copper-palladium catalysts prepared from organometallic precursor have been tested in the hydrogenation of phenylacetylene and in the hydrogenation/isomerization of the but-l-ene. The structure and catalytic behaviour of the bimetallic catalysts depended on the different temperatures of reduction. The presence of CuO or Cu metal in an alloyed state with Pd influenced the two reactions. The system containing CuO is the most active and selective towards the formation of the monoalkene in the hydrogenation of the highly unsaturated hydrocarbon. The system containing Cu partially alloyed with Pd is more active and selective towards the isomerization of the but-l-ene. The performance in the two reactions is discussed in terms of the electronic effect prevailing when CuO is present and in terms of the geometric ensemble size variation prevailing with the Cu-Pd system.