Ultrasonic velocity is a fundamental property to study the physical and chemical behaviour of pure liquids and liquid mixtures. In this paper, we propose the new expressions for velocity of pure organic liquids. The sound velocity has been calculated by using experimental value of density and the literature values of critical volume (Vc) and critical temperature (Tc). The values of sound velocity have been evaluated theoretically using three new different methods. Further, the predicted theoretical velocities were compared with the experimental findings. This new expressions are shown to represent the experimental velocity data of 27 different polar organic liquids can be predicted within 5.81% to 10.7% absolute average deviation(AAD) for all temperature investigated.