Excess molar enthalpies, H_m ^E, for the ternary mixture n-propanol (n-PrOH) + n-propyl acetate (n-PrOAc) + water (H₂O) were measured at 313.15 K and standard pressure (101.303 kPa) using the Setaram C80 calorimeter. The experimental results on the ternary system were fitted with the Redlich–Kister equation and NRTL model. The comparison of calculation results based on the set of parameters obtained from the data for only binary systems and on the set of parameters derived using both binary and ternary data was performed.