Density, (rho), and speed of sound, (u), from T= 288.15 to T= 308.15 K, and excess molar enthalpies, (h(E)) at T= 298.15 K, have been measured over the entire composition range for (methyl tert-butyl ether + 1-butanol + n-hexane). In addition, excess molar volumes, V-E, and excess isentropic compressibility, K-s(E), were calculated from experimental data. Finally, experimental excess enthalpies results are S compared with the estimations obtained by applying the group-contribution models of UNIFAC (in the versions of Dang and Tassios, Larsen et al., Gmehling et al.), and DISQUAC. (c) 2007 Elsevier Ltd. All rights reserved.