The ultrasonic velocity, density and viscosity have been measured for the ternary mixtures of benzene, chlorobenzene and nitrobenzene with N-N di methylformamide (DMF) in cyclohexane at 303K. The experimental data have been used to ca lculate the acoustical parameters namely adiabatic compressibility ( β ), free length (L f ), free volume (V f ), internal pressure ( π i ), viscous relaxation time ( τ ), Gibbs’ Free Energy ( ∆ G*) and acoustic impedance (Z). The excess values o f some the above parameters are also evaluated and di scussed in the light of molecular interaction in the mixtures. It is observed that a weak molecul ar interaction prevailing in the present systems of the mixtures. Such interactions are primarily du e to weak dipole-dipole and dipole- induced dipole types. Dispersive forces are also found to e xist between the components of the mixtures.