A study has been conducted on Acoustic Parameters of Heavy Fuel Oil- n-Heptane system. on different concentration’s[1.0%,0.9%,0.8%,0.7% and 0.6%] at different temperature’s of 30 oC, 35 oC, 40 oC, 45 oC and 50oC using Ultrasonic interferometer. Parameters like Ultrasonic velocity, Viscosity, Density, Adiabatic compressibility, Acoustic Impedance, Free length, Free Volume, Relation Time, Relative Association, Adsorption Coefficient and Molar compressibility are measured and helpful for correlation of Molecular interaction