The solubilities of p-methylbenzene sulfonic acid in supercritical carbon dioxide were determined at (308, 318, and 328) K and in the pressure range from (8 to 21) MPa. The effects of cosolvents (ethyl acetate, ethyl acetate + ethanol (molar ratio 1: 1), ethanol, and acetone) on the solubility of p-methylbenzene sulfonic acid were studied at a concentration of 1.5 mol %. The measured solubilities in supercritical carbon dioxide in the absence and presence of cosolvents were correlated using the Chrastil and modified Chrastil equation with good results, respectively.