Vapor-liquid equilibrium compositions were measured for the ternary system H-2-n-hexane-dicyclopentadiene at temperatures from 313 to 363 K and pressures from 2.0 to 5.5 MPa. The Peng-Robinson equation of state incorporated with a modified alpha expression was found to correlate the experimental data satisfactorily. Henry’s constants for the solubility of hydrogen in the liquid mixture were also provided in this study.