Abstract: The invention herein relates to a catalyst for enhancing the conversion of the dehydrogenation reaction of aromatic hydrocarbons such as ethylbenzene under a flow of carbon dioxide, which is expressed by the following formula I, wherein a catalyst in which an active component of iron oxides is highly dispersed onto a zeolite, activated charcoal, .gamma.-alumina or silica carrier. Further, the invention relates to a dehydrogenation method of aromatic hydrocarbons by means of using said catalyst:(Fe.sup.II.sub.x Fe.sup.III.sub.y O.sub.z)/S (I)wherein S denotes a zeolite, activated charcoal, .gamma.-alumina or silica carrier, and the initial state of iron oxide is as follows:x=0.