In this work, the solubility and liquid-phase mass transfer coefficient of hydrogen (H-2) in catalytic diesel at temperatures (353.2-453.2 K) and pressures (1-6 MPa) were measured experimentally. The solubility increases with the increase of pressure and temperature, and the Henry's constant follows the relation of In H (MPa) = 2447.02/T (K) - 0.11 with temperature. The molar fraction of H-2 and system pressure at different equilibrium time were measured to estimate the liquid phase mass transfer coefficient, and the results showed that with the increase of pressure the mass transfer coefficient increases. Furthermore, the solubility of H-2 in diesel was predicted by the COSMO-RS model using six virtual model compounds. Both the experimental data and predicted values agree well. Then, the solubility of H-2 in several hydrocarbon components with the same carbon atom but different ratios of C to H atoms was also predicted, and the results showed that the solubility decreases with the increase of the degree of unsaturation for hydrocarbons. Moreover, the H-2 solubility behavior in catalytic diesel was further explained from a molecular point of view by means of the COSMO-RS model.