The thermodynamic parameters viz. excess molar volume V-E and ultrasonic speed u, transport parameter viscosity eta, and spectroscopic parameters viz. IR, H-1, C-13 NMR have been measured for the mixtures of isomeric butanediol (1,2-, 1,3-, 1,4- and 2,3-butanediol) and N,N-dimethylformamide over the whole composition range at 308.15 K. The partial molar quantities Q(i)(E), isentropic compressibility K-S(E), deviation in ultrasonic velocity u(D), viscosity deviation Delta eta, deviation in Gibbs energies of activation for viscous flow g(x), and excess NMR chemical shift delta(E) have also been estimated and analyzed. Results show that the interaction between unlike molecules takes place through hydroxyl groups of isomeric butanediol and CO group of N,N-dimethylformamide. Excellent correlation between thermodynamic and spectroscopic measurements is observed. (C) 2005 Elsevier Ltd. All rights reserved.