Detailed characterizations and catalytic properties of pure ZnFe₂O₄, α-Fe₂O₃ and the biphasic catalysts are reported. It has been found that the biphasic catalysts containing ZnFe₂ O₄ and α-Fe₂O₃ exhibit remarkably improved catalytic activity with respect to each component. The observed phenomenon can be explained in terms of a synergetic effect. The results of the oxidative dehydrogenation of n-butenes over the pure phases and the biphasic catalyst at O₂–C₄H₈ ratios ranging from conditions of oxygen deficiency to excess oxygen suggest that there may be a possible function distribution between ZnFe₂O₄ and α-Fe₂O₃ of the ferrite catalyst. The results of the oxidation reaction of n-butenes in the absence of gas-phase oxygen over the pure phases and the biphasic catalyst containing 55.5%α-Fe₂O₃ indicate that the biphasic catalyst exhibits a longer active life than each of the two pure phases. Characterization of the pure phases and biphasic catalyst by X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and Mössbauer spectroscopy before and after the oxidation reaction of butenes in the absence of gas-phase oxygen reveals that α-Fe₂O₃ in the biaphasic catalyst was more easily reduced by butene than pure α-Fe₂O₃. With the catalytic behaviour of the pure phases and the biphasic catalyst taken into account, a synergetically catalytic mechanism for the ferrite biphasic catalyst is proposed.