Liquid liquid equilibrium (LLE) data for systems involving 1-butanol + water + protic ionic liquids ethyl-2-hydroxyethylammonium propionate [E2HEA][Pr], diethylammonium propionate [DEA]]Pr], or butylammonium propionate [BA][Pr] were determined at 298.15 K and atmospheric pressure. The solubility curves were obtained by the cloud point method and correlated with different empirical equations. The compositions of the phases in equilibrium were determined on the basis of the fitting equation of the binodal curve and the lever rule. Data quality was verified using the semiempirical methods by Othmer-Tobias and Hand. The liquid liquid equilibrium data were correlated using the Non-Random Two-Liquid (NRTL) model and the UNIversalQUAsi Chemical (UNIQUAC) model, and a good fit was found between the correlations and the experimental data, yielding overall root-mean-square deviations of 0.76% for NRTL and 0.95% for UNIQUAC.