Thermophysical parameters viz. excess molar volume V-E, speed of sound u, viscosity g and spectroscopic parameters viz. FT-IR, H-1 and C-13 NMR have been measured for the ternary liquid mixtures of {isomeric butanediol (butane-1,2-diol, butane-1,3-diol, butane-1,4-diol, butane-2,3-diol) + pyrrolidin-2-one} in beta-cyclodextrin over the whole composition range at T = 308.15 K. The deviation in the isentropic compressibility Delta kappa(S), partial molar quantities Q(i)(E), deviation in viscosity Delta eta, deviation in Gibbs energy of activation for viscous flow g(x) and excess NMR chemical shift delta(E) have been estimated and analysed. Results indicate that the position of hydroxyl groups of butanediol showed a noticeable effect on the thermophysical properties. Furthermore, the effect of addition of beta-cyclodextrin caused significant changes, due to difference in the fitting of isomeric butanediol in the hydrophobic cavity of beta-cyclodextrin. Particularly, visible changes in thermophysical properties of 1,4-BTD system have been observed in comparison to other isomers of BTD indicating that hydrogen bonding and affinity of fitting between (1,4-BTD and beta-CD + PY) are greater than the other isomers. These results have been found to be in excellent concurrence with NMR and FT-IR studies. However, for 2,3-BTD and 1,3-BTD systems dispersion forces due to dissociation of self-associated PY and diols are predominant. The spectroscopic measurements (FT-IR, H-1 and C-13 NMR) confirm that the interaction between unlike molecules take place through hydroxyl groups of isomeric butanediol and carbonyl group of pyrrolidin-2-one. (C) 2012 Elsevier Ltd. All rights reserved.