AN IMPROVED PROCESS IS PROVIDED FOR THE SELECTIVE REDUCTION OF ALKYNES OR 1,3-CONJUGATED DIENES IN ADMIXTURE WITH ALKENES WHEREBY THE ALKNES OR 1,3-CONJUGATED DIENES ARE SUBSTANTIALLY SELECTIVELY REDUCED TO THE CORRESPONDING ALKENES WITHOUT UNDUE REDUCTION OF THE ALKENES TO THE ALKANES. THE IMPROVEMENT COMPRISES CARRYING OUT THE REDUCTION IN THE PRESENCE OF A TRANSITION METAL CATALYST INTERCALATED IN GRAPHITE WHEREIN THE TRANSITION METAL IS IN THE METALLIC STATE HAVING A ZERO VALENCE. THE TRANSITION METAL IS SELECTED FROM NICKEL, PALLADIUM AND PLATINUM.