Experimental isothermal P-x-y data for the ternary systems methyl tert-butyl ether + heptane + cyclohexane and methyl tert-butyl ether + cyclohexane + l-hexene at 313.15 K and for the binaries cyclohexane + heptane and cyclohexane + l-hexene at 313.15 K are reported. Data reduction by Barker＇s method provides correlations for GE, using the Margules equation for the binary systems and the Wohl expansion for the ternaries. Wilson, NRTL, and UNIQUAC models have been applied sucessfully to both the binary and the ternary systems presented here.