The ultrasonic technique was used for measuring the interfacial area (a) in a gas-liquid bubble column. In this study, the ultrasonic technique is based on the measurement of the attenuation of the ultrasound pulses propagating through a gas-liquid dispersion system. The characterization of gas-liquid dispersion using ultrasound might prove a very valuable alternative for situations in which conventional techniques such as those based on optical principles cannot be applied. The effects of several parameters such as ultrasound pathlength, bubble diameter, and liquid physical property on the attenuation of ultrasound were studied. Based on the experimental data, a linear correlation for interfacial area prediction is derived. The results of the ultrasonic technique are in good agreement with those of the physical method under the current experimental condition.