Thermodynamic consideration of the dehydrogenation of ethylbenzene clearly indicates that the equilibrium yield of styrene for the dehydrogenation in the presence of CO2 is much higher than that for the dehydrogenation in the presence of steam. A two-step pathway for the dehydrogenation in the presence of CO2 appears to provide higher equilibrium yield of styrene at a given temperature. The amount of energy required for the new process using CO2 is much lower than that for a typical present commercial process using steam. An Fe2O3(10 wt.%)/Al2O3 (90 wt.%) catalyst prepared by a coprecipitation method was found to be effective for the dehydrogenation of ethylbenzene to produce styrene in the presence of CO2. (C)2000 Elsevier Science B.V. All rights reserved.