The ultrasonic speeds, u and viscosities, eta of binary mixtures of formamide (FA) with 1-butanol, 2-butanol, 1,3-butanediol and 1,4-butanediol, including those of pure liquids, over the entire composition range were measured at temperatures 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K. From the experimental u and eta data, the deviations in isentropic compressibility, Delta k(s), in ultrasonic speed, Delta u, and in viscosity, Delta eta were calculated. The partial molar compressibilities, (K) over bar (m.1) and (K) over bar (m.2) of FA and alkanol in the mixtures over the whole composition range and (K) over bar (m.1)degrees and (K) over bar (m.2)degrees at infinite dilution and excess partial molar compressibilities, (K) over bar (E)(m.1) and (K) over bar (E)(m.2), over the whole composition range and (K) over bar (m.1)degrees(E) and (K) over bar (m.2)degrees(E) at infinite dilution were calculated by using two different approaches. The variations of these parameters with composition and temperature of the mixtures are discussed in terms of molecular interaction in these mixtures. It is observed that the FA-alkanol interactions in these mixtures follows the order: 1-butanol < 2-butanol < 1,3-butanediol < 1,4-butanediol. The effect of the number and position of the hydroxyl groups in these alkanol molecules on the molecular interactions in these mixtures is discussed. Furthermore, the free energies, Delta G*, enthalpies, Delta H*, and entropies, Delta S* of activation of viscous flow have also been obtained by using Eyring viscosity equation. The dependence of Delta G*, Delta H* and Delta S* on composition of the mixtures have been discussed. (c) 2008 Elsevier B.V. All rights reserved.