Co9Fe3Bi1Mo12O51 catalysts were prepared by two different methods, and were applied to the oxidative dehydrogenation of n-butene to 1,3-butadiene in a continuous flow fixed-bed reactor. Co9Fe3Bi1Mo12O51-SG catalyst prepared by a citric acid-derived sol-gel method exhibited a higher yield for 1,3-butadiene than Co9Fe3Bi1Mo12O51-CP catalyst prepared by a co-precipitation method. It was revealed that the Co9Fe3Bi1Mo12O51-SG catalyst retained abundant oxygen species for the reaction and sufficient adsorption sites for n-butene compared to the Co9Fe3Bi1Mo12O51-CP catalyst, leading to an enhanced catalytic performance of Co9Fe3Bi1Mo12O51-SG in the oxidative dehydrogenation of n-butene.