Liquid-liquid equilibria for the ternary system water + propionic acid + 2-butanol was measured over a temperature range of 298 to 318 K. The results were used to estimate the interaction parameters between each of the three compounds for the nonrandom, two liquid (NRTL) equilibrium model as a function of temperature. The estimated interaction parameters were successfully used to predict the equilibrium compositions by the NRTL model. Based on this work, the distribution coefficients were also calculated and compared with the experimental values.