The solubility of H-2 in alkylic and aromatic hydrocarbons was quantum-chemical theoretically calculated through the conductor-like screening model for real solvents (COSMO-RS). The results show that COSMO-RS provides qualitative values of the H-2 solubilities and describes correctly their increasing trends with temperature, pressure, alkylic-chain length, and number of aromatic rings. The H-2 solubility is explained in terms of the screening charge density, that is, the small polarizations of H-2 and hydrocarbons suffice for them to attractively interact. Solubility parameters give additional support to these results.