A semiflow type apparatus for solid solute solubility measurement was constructed to investigate the solubility of isomers of methylsalicylic acid (MSA) in supercritical carbon dioxide (ScCO2). The solubility of salicylic acid in ScCO2 was measured in seeking to validate the reliability of the apparatus and the experimental procedure. The solubility of three MSA isomers, 3MSA, 4-MSA, and 5-MSA, were measured at 308.2, 318.2, and 328.2 K, respectively, over a pressure range of 9-18.5 MPa. The results showed that the solubility of MSA isomers was within the range of 8.3 X 10(-6) and 5.9 X 10(-4). These newly measured solubility data were correlated by four semiempirical models; satisfactory correlation results were obtained with the average absolute relative deviation in solubility within 8.17%. The consistency of the solubility data was confirmed by the good correlation results with the Chrastil and Mendez-Santiago and Teja models.