In order to separate o-cresol from wastewater and supplement the related parameters of o-cresol + solvent (isoamyl alcohol), the liquid–liquid equilibrium (LLE) data of isoamyl alcohol + o-cresol + water was determined at 298.2, 308.2 and 318.2 K, under 101.3 kPa. Comparing the distribution coefficients (D) and separation factors (S) of isoamyl alcohol, it is found that the isoamyl alcohol was great for extracting o-cresol from water. The consistency was verified by the Othmer–Tobias and Hand equations. Meanwhile, the NRTL and UNIQUAC thermodynamic models of this system were correlated using Aspen Plus 8.4. The root mean square deviation (RMSD) values were less than 0.42%. In addition, the reliability of regression parameters was verified using the GUI-MATLAB tool. [ABSTRACT FROM AUTHOR]