The experimental liquid-liquid equilibrium data on propionic acid-water-solvent ternary mixtures at a temperature of 298.15 K are presented. The solvents are n-hexane, cyclohexane, cyclohexanol and cyclohexyl acetate. The distribution coefficients and separation factors are reported. The tie line data are correlated using the methods of Othmer-Tobias and Hand. The experimental results are compared with the values predicted by the UNIFAC group-contribution method.