The solubility of o-aminobenzamide (o-AB) and its mixture with o-nitrobenzoic acid (o-NBA) in subcritical 1,1,1,2-tetrafluoroethane (R134a) was measured at temperatures of 308, 318, 328 K and pressure range from 5.0 to 15.0 MPa with static method. Then the solubility of o-AB and o-NBA in subcritical R134a binary and ternary system were compared and investigated from the view of solvent density, solvent polarity, and interaction between solvent and solute. In order to evaluate the effect of co-solute on solubility of solute, enhancement factor (EF), separation factor (SF), separation efficiency (SE), and the solubility enhancement coefficient (alpha) were defined and calculated. In addition, empirical models, including Chrastil, A-L, K-J, S-S, and M-T models applying for binary system, with Gonzalez, Sovova, M-M-T, and Z-J models applying for ternary system, are used for correlating the experimental solubility. The satisfactory correlated results were obtained with the AARD range from 2.16% to 4.75%. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.