A new quasistatic technique has been presented in a previous paper [G. Anitescu, L.L. Tavlarides, J. Supercritical Fluids (1997)] [1] and employed to obtain solubilities of polycyclic aromatic hydrocarbons (PAHs) in the pure supercritical fluids (SCFs) carbon dioxide and ethane. This paper extends the method to determine the solubilities of PAHs in the solvent/cosolvent SCFs. The equipment and procedure were modified to include a precise cosolvent delivery system. Extensive solubility data of anthracene, phenanthrene, pyrene, and perylene in the SCFs CO2/C2H6, CO2/C3H8, CO2/n-C4H10 and CO2/MeOH are presented at 313 and 333 K in a pressure range of 100-350 bar for mole fractions of the cosolvent of 0.05 and 0.10. Solubilities of phenanthrene in CO2/C2H6 at 313 K were performed for the entire range of SCF compositions. In terms of the absolute magnitude of solubility, the CO2/cosolvent power increases for the studied systems related to pure carbon dioxide in the order CO2/ethane (16-30%) < CO2/propane (24-56%) < CO2/n-butane (35-79%) < CO2/methanol (66-84%).