The measurement of ultrasonic velocity, density and viscosity has been made for the ternary liquid mixtures of 1- pentanol and 1-hexanol with decane in cyclohexane at different temperatures (303 K, 308 K and 313 K). Acoustic parameters such as adiabatic compressibility, intermolecular free length, free volume and internal pressure have been evaluated. Weak molecular interaction taking part between the unlike molecules of solute in each mixture have been studied through these acoustical parameters and their excess values.
