Liquid-liquid equilibria (LLE) for the systems 1-propanol + water + K2HPO4 and 2-propanol + water + K2HPO4 were measured at temperatures of (288.15, 298.15, and 308.15) K. The binodal curves of the systems were fitted to a nonlinear equation relating the mass fraction of 1- or 2-propanol to that of K2HPO4, and the tie lines were successfully correlated with the Othmer-Tobias and Bancroft equations. LLE results were predicted using a pair of the binodal and Bancroft equations and one of the binodal and Othmer- Tobias equations. Both predictions showed close agreement with experimental values, and the average root-mean-square deviations of the values predicted from the former pair were 0.28% and 0.27% for the systems 1- propanol + water + K2HPO4 and 2-propanol + water + K2HPO4, respectively.