The oxidative dehydrogenation of butene to butadiene over U-Sb catalysts was investigated. The presence of two compds., (UO2)Sb3O7 and Sb3U3O14, reported by Grasselli and Callahan (1969), was confirmed with (UO2)Sb3O7 being the actual catalyst. The reaction is first order in butene and zero order in O. In the absence of O, interaction of butene with the catalyst O occurred but only to a minor degree, the interaction being confined to the surface. Partial reactivation by heating of a catalyst inactivated by the interaction with butene in the absence of O could be effected, but there exists a tendency for the catalyst to decomp. A remarkable detail in the kinetics is that, contrary to the reaction over Bi-Mo catalyst, double-bond isomerization is absent.