In this work the applicability of simple mixing rules combined with Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) equations of state was tested in the prediction of excess molar volume for high polar and partially miscible multicomponent mixtures. To this aim the temperature trend of excess molar volumes of the ternary mixture acetone+methanol+n-hexane was measured in the range 278.15-298.15 K and atmospheric pressure. The corresponding interaction parameters were computed. Good accuracy was obtained in general terms when predicting ternary values of the magnitude. 1999 Elsevier Science B.V. All rights reserved.