Oxidative dehydrogenation of C-4 raffinate-3 to 1,3-butadiene was carried out in a dual-bed reaction system comprising ZnFe2O4 and Co9Fe3Bi1Mo12O51 catalysts in order to investigate a synergistic effect of these two catalysts. Conversion of n-butene and yield for 1,3-butiadene obtained in a dual-bed reaction system comprising ZnFe2O4 (first-bed) and Co9Fe3Bi1Mo12O51 (second-bed) were higher than those obtained in a single-bed reaction system using either ZnFe2O4 or Co9Fe3Bi1Mo12O51. 1-Butene-TPD and 2-butene-TPD measurements revealed that ZnFe2O4 catalyst retained more selective oxygen species for the reaction with 2-butene than for the reaction with 1-butene, while Co9Fe3Bi1Mo12O51 catalyst retained more selective oxygen species for the reaction with 1-butene than for the reaction with 2-butene. The synergistic effect of ZnFe2O4 (first-bed) and Co9Fe3Bi1Mo12O51 (second-bed) catalysts in the oxidative dehydrogenation of C-4 raffinate-3 was attributed to the combination of high catalytic activity of ZnFe2O4 for 2-butene and high catalytic activity of Co9Fe3Bi1Mo12O51 for 1-butene.