Measurements of excess molar enthalpies at the temperature 298.15 K in a flow microcalorimeter, are reported for the ternary mixtures {x(1)C(4)H(8)O+x(2)(CH3)(3)CCH2 CH(CH3)(2) + (1 - x(1) - x(2))C6H11CH3} and {x(1)C(4)H(8)O + x(2)C(7)H(16) + (1 - x(1) - x(2))C6H11 CH3} Smooth representations of the results are described and used to construct constantenthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann-Fried model, using only the physical properties of the components and their binary Mixtures.