Excess molar enthalpies, H-m(E), for the ternary mixture n-propanol (n-PrOH) + acetic acid (AcOH)+ water (H2O) were measured at 313.15 K and atmospheric pressure using the Setaram C80 calorimeter. The data for initial binary sub-systems were taken from the literature and correlated with the Redlich-Kister equation. The experimental results on the ternary system were fitted by means of different variable degree polynomials. Smooth representations of the results were used to construct constant excess molar enthalpy contours on Roozeboom diagram. The capability of the NRTL model to predict excess molar enthalpies for the ternary systems based on the data for the binary sub-systems was considered. (C) 2015 Elsevier B.V. All rights reserved.