In the present work, quantification of the overall gas-liquid mass-transfer coefficient (K(L)a) in the sonochemical reactors (two different types viz. ultrasonic horn and ultrasonic bath) has been done using the dynamic method. The effect of operating parameters such as the power density into the system, gas flow rate, position of the sparger relative to the ultrasound source, and the presence of sodium chloride (as an electrolyte) on the mass-transfer coefficient has been investigated. Correlations have been developed for the prediction of the volumetric mass-transfer coefficient for liquids in both types of ultrasonic reactors. The information obtained in the present work should be useful in understanding the role of gas-liquid mass transfer in a gas-liquid reaction system using ultrasound as a source of the supply of the energy and should be a breakthrough in the design procedure as no studies of this kind are currently available in the open literature.