Experimental excess enthalpies of the ternary system tert-amyl methyl ether (TAME) + tert-amyl alcohol (TAOH) + hexane and the corresponding binary subsystems at 313.15 K are reported. Also the systems TAME + TAOH and TAOH + hexane have been measured at 298.15 K. A quasi-isothermal flow calorimeter has been modified and tested to make the measurements. The experimental data have been fitted using a polynomial equation for binary and ternary systems. The values of the standard deviation indicate the agreement between the experimental results and the fitted ones. Positive experimental excess enthalpies were obtained for all compositions of the ternary mixture investigated. which are larger than for the binary subsystems. Temperature increase from 298.15 to 313.15 K enhances endothermic effect in the binary subsystems, TAME + TAOH and TAOH + hexane, studied here. Excess Gibbs energy data published previously and excess enthalpies have been used for calculating the excess entropy of the binary and ternary systems at 313.15 K. (C) 2003 Published by Elsevier B.V.