The oxidative dehydrogenation of 1-butene to butadiene was studied over a series of catalysts of iron impregnated on ZnAl2O4 used as a support and also Fe coprecipitated with zinc and aluminum in order to obtain ZnFexAl2-xO4 type catalysts. Results were compared with bulk alpha-Fe2O3, ZnAl2O4 and ZnFe2O4. X-ray diffraction (XRD) and Mossbauer spectroscopy suggest that in the impregnated catalysts, Fe ions are in strong interaction with the support. These samples have higher butadiene selectivity than coprecipitated ZnFexAl2-xO4 catalysts, in which iron is incorporated into the ZnAl2O4 spinel network. Results suggest also that iron content has a greater effect on butadiene selectivity than the zinc aluminate-iron oxide interaction.