This study demonstrates the experimental solubility and tie-line data for (water + phosphoric acid + isoamyl acetate or methyl isoamyl ketone) ternary systems at T=(298.2, 308.2, and 318.2)K and atmospheric pressure for the first time. The concentration of each phase was determined by acidimetric titration, the Karl Fischer technique, and refractive index measurements. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental data was determined through the Othmer-Tobias and Hand plots. Distribution coefficients and separation factors were evaluated over the immiscibility regions. (C) 2012 Elsevier B.V. All rights reserved.