Abstract: The IRspectra of adspecies of ethylbenzene and ethylbenzene-d₁₀ were observed at the room temp and reaction temp,respectively.The relative rates of dehydrogenation of several kinds of deuterium labelled ethylbenzene have been determined under the same reaction conditions.Apossible mechanistic pathway for the dehydrogenation of ethylbenzene may then be proposed as following.First,the ethylbenzene molecule is adsorbed on the iron oxide catalyst surface,the α-His abstracted by lattice oxygen of the catalyst to form a surface-OH,and a pseudo π-allyl intermediate of the ethylbenzene residual,which may be coverted to a pseudo σ-allyl intermediate The β-Hmay then be ruptured to form styrene molecule and a Fe-Hbond on a neighbouring Fe⁺²⁽⁺³⁾in the rate determining step.