The solubility of hydrogen in toluene in the presence of the compressed CO, at the temperatures from 305 to 343 K and the pressures from 1.2 to 10.5 MPa was measured by using a continuous flow technique. The obtained data indicate that more hydrogen could be dissolved in toluene at the pressures higher than a certain value depending on temperature and the molar ratio of H-2 to CO2 in gas. The Peng-Robinson equation of state associated with the van der Waals mixing rule were found to correlate the VLE data of the ternary system H-2 + CO2 + toluene satisfactorily. From the volume expansion resulted from the dissolution of CO2 in toluene calculated by the proposed model, it was found that hydrogen Solubility was generally increased with increasing volume expansion. A large volume expansion was required to enhance hydrogen solubility when the mole fraction of hydrogen in gas was low. (c) 2006 Elsevier B.V. All rights reserved.