The equilibrium solubilities of ammonium benzoate (ABE) and its mixture with benzamide (BZE) in supercritical carbon dioxide were measured at temperatures ranging from 308 to 328 K and pressures from 11.0 to 21.0 MPa using a dynamic flow method. The solubility of ABE in binary (ABE + CO2) system was correlated by 4 semi-empirical models (Chrastil, K-J, M-T and Yu); 2 semi-empirical models (T-G and Sovova) were used to correlate the solubility of ABE in ternary system (ABE + BZE + CO2). In ternary system, both the solubilities decreased as compared to their binary system, the reduction factor (e) and selectivity (alpha) are defined and calculated respectively. The differences between the solubilities of solid solute in binary and ternary systems were analyzed based on the assumption of molecular competition. (C) 2012 Elsevier B.V. All rights reserved.