The gas-liquid mass transfer in the co-current three-phase fluidized bed with non-Newtonian liquids was studied. Gas hold-ups (phi(g))and volumetric gas-liquid mass transfer coefficients (k(L)a) in a bed of glass beads fluidized in non-Newtonian liquids with gas phase were measured. The gas hold-ups affecting gas-liquid mass transfer rate increased and decreased with increasing particle size and liquid velocity, respectively. The k(L)a coefficients were evaluated from the dynamic gassing-out method based on the tanks-in-series model describing non-ideal mixing in the three-phase fluidized bed. While an increase in the liquid velocity decreased the k(L)a coefficient, an increase in the particle size enhanced the k(L)a coefficient. The increase in purely viscous non-Newtonian flow behaviors reduced gas hold-up and gas-liquid mass transfer rate because of the bubble coalescing nature of the highly viscous non-Newtonian fluid. The theoretical models for phi(g) and k(L)a in three-phase fluidized beds with non-Newtonian fluids were developed on the basis of the energy dissipation rate. They could reasonably fit the present experimental data. (c) 2012 Elsevier B.V. All rights reserved.