Local overall gas-liquid mass transfer coefficients (K(L)a) of gas-liquid-solid three-phase reversed flow jet loop reactors have been experimentally investigated by means of a transient gassing-in method. Effects of liquid jet flow rate, gas jet flow rate, particle density, particle diameter, solid loading, nozzle diameter and axial position on local overall gas-liquid mass transfer coefficient profiles are discussed. It was observed that the local overall gas-liquid mass transfer coefficient profiles of the reversed flow jet loop reactor with a three-phase system increase with increase in gas jet flow rates and liquid jet flow rates and particle density and particle diameter, and with decrease in nozzle diameter and axial position. The presence of solids at low concentrations, increases the local overall gas-liquid mass transfer coefficient profiles, and the optimum of adding solid loading for maximum profile of the local overall K(L)a was found to be 0.16 x 10(-3) m(3) corresponding to a solid volume fraction, epsilon(S) = 2.5%.