Densities, rho and speeds of sound, u of tetrahydropyran (i)+ pyridine or alpha-, beta- or gamma- picoline (j) binary mixtures at 298.15, 303.15 and 308.15 K and excess molar enthalpies, H-E of the same set of mixtures at 308.15 K have been measured as a function of composition using an anton Parr vibrating-tube digital density and sound analyzer (model DSA 5000) and 2-drop micro-calorimeter, respectively. The resulting density and speed of sound data of the investigated mixtures have been utilized to predict excess molar volumes, V-E and excess isentropic compressibilities, kappa(E)(S). The observed data have been analyzed in terms of (i) Graph theory; (ii) Prigogine-Flory-Patterson theory. It has been observed that V-E, H-E and kappa(E)(S) data predicted by Graph theory compare well with their experimental values. (C) 2011 Elsevier B.V. All rights reserved.