The effect of the addition of compressed carbon dioxide in continuous hydrogenation of toluene has been evaluated with process simulation software and tested with a fixed-bed reactor. The simulation results show that the temperature rise is significantly suppressed in the presence of compressed carbon dioxide and that the equilibrium conversion of toluene (toluene/hydrogen = 1/3) reaches 99.9%, whereas around 60% in the absence of carbon dioxide. Experimental results show that the continuous hydrogenation of toluene (toluene/hydrogen/carbon dioxide = 1/3.1/31, inlet temperature: 20 degrees C, outlet temperature: <70 degrees C, and total pressure: 11 MPa) over activated carbon-supported rhodium catalysts proceeds without deactivation. The conversion of toluene reaches 99% and methylcyclohexane is the only product detected.