Liquid-liquid phase equilibrium data for ternary systems containing formamide (or ethylene glycol (EG), monoethanolamine (MEA) + indole + 2-methylnaphthalene (2-MN) at 308.15 K under atmospheric pressure were measured in this work. The results show that all the three ternary systems are Treyball type 1 systems. The experimental data were correlated well using both the non-random two liquid (NRTL) model and universal quasi-chemical activity coefficient (UNIQUAC) model. In addition, both the distribution coefficient and selectivity coefficient of formamide, EG and MEA were calculated to investigate the feasibility of extracting indole from 2-MN and formamide presented a better selectivity. (C) 2015 Elsevier B.V. All rights reserved.