Excess molar volumes V-ijk(E), speeds of sound, u(ijk), of tetrahydropyran (i)+ benzene (j)+ cyclohexane or n-hexane or n-heptane (k) ternary mixtures have been measured as a function of composition at 308.15K and atmospheric pressure. The observed speeds of sound data of the investigated ternary mixtures have been utilized to calculate their excess isentropic compressibilities, (K-S(E))(ijk,) The and V-ijk(E) have been fitted to the Redlich-Kister equation to calculate ternary adjustable parameters and standard deviations. Connectivity parameters of third degree of the constituents of mixtures (which in turn depends on the topology of a molecule) have been employed to determine excess molar volumes, V, and excess isentropic compressibilities, (K-S(E))(ijk,) It has been observed that V-ijk(E) and (K-S(E))(ijk) values calculated by the Graph theory (which involves connectivity parameter of third degree of a molecule) compare well with their corresponding experimental values. (C) 2010 Elsevier B.V. All rights reserved.