Deuteration of buta-1, 3-diene, 2-methylbuta-1, 3-diene and penta-1, 3-diene selectively yielded but-2-ene, 2-methylbut-2-ene and 1, 4-[2H2] pent-2-ene on CdO and Co3O4, and but-1-ene, 2-methylbut-1-ene and 4, 5-[2H2] pent-2-ene on Cr2O3, respectively. These results imply that the selectivity for 1, 2-and 1, 4-hydrogen addition is maintained in hydrogenation of conjugated dienes, ie 1, 4-addition on CdO and Co3O4, and 1, 2- ...