Consistent vapor- liquid equilibrium ( VLE) data at 101.3 kPa have been determined for the ternary system dipropyl ether + 1- propyl alcohol + butyl propionate and two constituent binary systems: dipropyl ether + butyl propionate and 1- propyl alcohol + butyl propionate. The dipropyl ether + butyl propionate system exhibits ideal behavior, and the 1- propyl alcohol + butyl propionate system shows positive deviations from Raoult's law. No additional azeotropes are present. The activity coefficients of the solutions were correlated with its composition by the Wilson, NRTL, and UNIQUAC models. The ternary system is well- predicted from binary interaction parameters. Butyl propionate breaks the dipropyl ether/ 1- propyl alcohol binary azeotrope. However, the change of phase equilibria behavior is small; therefore, this solvent is not such an effective agent to this azeotrope mixture separation. In fact, the mean relative volatility on a solvent- free basis is 0.82 ( close to unity).