A conventional nonelectrolyte solution which has led to successful predictive expressions for the thermomechanical properties of a solute in simple binary solvent mixtures is extended to ternary systems havingACandAC2molecular complexes. The general mixing model used assumes that the Gibbs free energy of mixing and excess volume can be separated into a chemical and physical contribution. The chemical interaction term results from the formation of molecular complexes and the physical contribution describes nonspecific interactions between the uncomplexed and associated species in solution. TenAijparameters are initially needed to describe all binary nonspecific interactions present. Simplifying approximations and mathematical manipulations reduce the number of binary interaction parameters to only 3Aijvalues. Expressions derived from the general mixing model are used to estimate excess volumes of ternary acetone + cyclohexane + chloroform mixtures.