Excess molar volumes, V-E, excess isentropic compressibilities, kappa(E)(S) (obtained from the measured density, rho and speed of sound, u data), excess heat capacities, C-P(E) of o-chlorotoluene (i) + formamide or N-methylformamide or N, N-dimethylformamide (j) binary mixtures at T = (298.15. 303.15, 308.15) K and excess molar enthalpies, H-E of the same (i + j) mixtures at T = 308.15 K have been determined/measured over entire mole fraction using density and sound analyzer (DSA-5000) and micro differential scanning calorimeter [Model-mu DSC 7 Evo]. The V-E, kappa(E)(S); H-E and C-P(E) data have been analyzed in terms of (a) Graph; (b) Prigogine-Flory-Patterson; and (c) Sanchez-Lacombe's theories. It has been observed that V-E, kappa(E)(S), H-E and CEP values calculated from Graph theory compare well with their experimental values. (C) 2013 Elsevier Ltd. All rights reserved.