Ultrasonic velocity measurement provides an important tool to study the liquid state. The measurement of ultrasonic velocity in liquid mixture provides valuable information about their physico-chemical properties and nature of molecular interaction in them. Ultrasonic parameters provide valuable information about various inter and intra molecular interactions in solution. Cefotaxime sodium is used as an antibiotic in pharmaceutical. It is antibacterial, β-lactum; third generation cephalosporin. Ultrasonic velocity, density and viscosity of aqueous solution of cefotaxime sodium at different concentrations, temperatures and different frequencies such as 2MHz, 4MHz and 6MHz have been experimentally determined. Ultrasonic parameters such as adiabatic compressibility, intermolecular free length and relaxation time of these solutions are computed on the basis of these measurements. Various molecular interactions in these solutions have been analyzed on the basis of the variation of these parameters with concentration, temperature and frequency.