BiMoFex oxide catalysts (x = 0-1.00) were prepared by co-precipitation and their catalytic activities in the oxidative dehydrogenation of n-butenes were tested. X-ray diffraction (XRD) and Raman spectroscopy showed that the main solid phases were composed of Bi3Mo2FeO12 as oxygen acceptor and Fe-2(MoO4)(3) as oxygen donor and the mixing of these phases enhanced catalytic activity. XRD patterns showed that Fe-2(MoO4)(3) was reduced to FeMoO4 during the reaction. The peak temperature of programmed reduction of 1-butene and successive oxidation (TPRO) was dependent on Fe contents in BiMoFex oxide catalysts and was minimized at x = 0.65, which showed the greatest oxygen mobility. The peak position in the low temperature region of TPRO profiles could be correlated with butene conversion and BD yield. (c) 2012 Elsevier B.V. All rights reserved.