Density ( ρ ),Ultrasonic velocity (u), and viscosity ( η ) values have been measured in the binary system co ntaining quinoline and o-xylene at different temperatures 30 3.15K, 308.15K, 313.15K and 318.15K over the entire range of composition. The experimental data have been used t o calculate the ultrasonic parameters such as adiab atic compressibility ( β ), free length (L f ), free volume (V f ) and internal pressure ( π ). The results have been qualitatively used to explain the molecular interaction between t he components of the mixture.