A series of cobalt oxide (Co3O4) loaded (5-20wt%) gamma-Al2O3, MgO and SiO2 supported catalysts were prepared by wetness-impregnation method and tested for oxidative dehydrogenation (ODH) of ethylbenzene (EB) in vapor phase atmospheric pressure conditions. Among Co oxide doped catalysts, Co3O4/gamma-Al2O3 (CA) has afforded a superior catalytic activity in view of desirable EB conversion and styrene (ST) yields. Thus unusual catalytic properties of 15CA catalyst were supposed to be due to adequate acidic-basic nature, thermal stability and synergistic effect of Co-Al species along with uniform distribution of active Co oxide ions. Moreover, dramatic catalytic activity of Co3O4 incorporated gamma-Al2O3 catalyst can be explained on the basis of beneficial CO2 conversion subsequently production of better CO yields during the online gas analysis. All calcined catalysts have been characterized by different sophisticated techniques to elucidate the surface metal composition and influence of Co3O4 oxide species on catalytic activity presentation during the oxidative dehydrogenation of EB reaction.