Maleic acid, maleic anhydride or other hydrogenatable precursor are catalytically hydrogenated to 1,4-butanediol and tetrahydrofuran. It has been discovered that high yields of 1,4-butanediol are achieved when the hydrogenation catalyst comprises palladium, silver and rhenium on a carbon support and is prepared by the steps of(i) impregnating a carbon support with a source of palladium, silver and rhenium, wherein the source of palladium, silver and rhenium is at least one solution,(ii) after each impregnation step, drying the impregnated carbon support to remove solvent,(iii) heating the impregnated carbon support at a temperature of about 120.degree. C. to about 350.degree. C. under reducing conditions.The palladium in the catalyst is present in the form of crystallites having a particle size of less than 10 nm.