The effects of gas(0.01-0.12m/s) and liquid velocities(0.02-0.10m/s) and praticle size(1-8mm)on gas/liquid interfacial area(a) and mass transfer coefficient(k_L) have been determined in a 0.142m-I.D.×2.0m-high Plexiglas column. Gas-liquid interfacial area increases with increasing gas and liquid velocities, but it exibits a minimum value in the bed of 6.0mm particle. In the bubble coalescing regime, k_L is nearly independent of gas velocities. The effect of liquid velocity on k_L is found to be negligibly small. A minimum value of k_L exhibits the bed of 1.7mm particle. The liquid side mass transfer coefficient in terms of Sherwood number in three-phase fluidized beds have been correlated with Schmidt and particle Reynolds numbers related to the energy dissipation rate in the bed based on the local isotropic turbulence theory.