The experimental density and speed of ultrasound measurements in connection with literature data have been measured for pure N,N-dimethylformamide (DMF), methanol and their binary mixtures over the whole miscibility range at different temperatures 303, 308, 313, 318 and 323 K. These parameters were used to determine the adiabatic compressibility, intermolecular free length, molar compressibility, molar sound velocity, acoustic impedance, relaxation strength and their excess values. The variation of these parameters with composition of mixture indicates the nature and extent of interaction between unlike molecules. The non-ideal behavior of the system studied was explained on the basis of the dipole-induced dipole interactions and hydrogen bonding. The complex formation through intermolecular hydrogen bonding was confirmed from the recorded FTIR spectra. Available thermal energy breaks the bonds between the associated molecules into their respective monomers on increasing the temperature. (C) 2009 Elsevier B.V. All rights reserved.