In the present study, density, viscosity and ultrasonic velocity have been measured for ternary liquid system of Riboflavin with water and methanol at 288 K in the concentration range 0.00 to 0.1 M. These measured values and derived parameters were used to performed molecular interaction study at 2 MHz using ultrasonic interferometer technique. The results of reported study have been thoroughly analysed and eventually interpreted at the possible molecular interaction such as structure making, solute-solvent and hydrogen bonding effect in the liquid solution of Riboflavin with water and methanol.