Abstract: A catalyst is described for selective gas phase hydrogenation of acetylenic compounds containing 2 or 3 carbon atoms to the corresponding ethylenic compounds. The catalyst, in the form of spherules or extrudates, comprises palladium, at least one metal from group IB, optionally at least one alkali or alkaline-earth metal, and alumina, in which at least 80% of the palladium and at least 80% of the element from group IB are present in a volume at the periphery of the catalyst defined between a spherical or cylindrical surface with radius r.sub.1 corresponding to the average radius of the spherules or extrudates of the catalyst and a spherical or cylindrical surface with radius r.sub.2 at least equal to 0.8 r.sub.1, the catalyst having a group IB metal/palladium ratio of 0.4 to 3 by weight. Further, it is advantageous for this catalyst that at least 30% of the metal particles contain both palladium and silver.