Experimental isothermal P-x data at T = 313.15 K for the binary systems 1,1-dimethylethyl methyl ether (MTBE) + n-hexane and methanol + n-hexane, and the ternary system MTBE + methanol + n-hexane are reported. Data reduction by Barker's method provides correlations for G(E) using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems. Moreover, we compare the experimental results for these binary mixtures to the prediction of the UNIFAC (Dortmund) model. Experimental results have been compared to predictions for the ternary system obtained from the Wilson, NRTL, UNIQUAC and UNIFAC models; for the ternary system, the UNIFAC predictions seem poor. The presence of azeotropes in the binary systems has been studied. (C) 2003 Elsevier B.V. All rights reserved.