We have measured ultrasonic absorption and velocity in aqueous solution of NaTC(bile salt) in water as a function of temperature and frequency. Ultrasonic absorption measurements have been done in frequency range 5 to 35MHz using pulse-echo technique. Ultrasonic velocity measurements were performed at fixed frequency 2MHz using interferometric technique. Relaxation frequencies have been evaluated using experimental data of absorption at different temperatures. The lyotropic liquid crystalline phase due to micelle formation took place at ï»350C at critical concentration 58.4 gm/1000ml ofNaTC inwater.