The solubilities of the diamondoids, adamantane and diamantane, in carbon dioxide, ethane, and methane have been measured using a flow apparatus at 333 It (the solubility of diamantane in methane was measured at 353 K) and pressures ranging from 5.31 MPa to 20.10 MPa. The data were correlated as functions of the solvent density and also using the Patel-Teja equation of state. Solubility enhancement for each diamondoid followed regular behavior with respect to the solvent density.