A draft-tube spouted-bed (DTSB) reactor was equipped with an auxiliary aeration device to provide air into the annular region and thereby improve the oxygen transfer efficiency. The effects of the total air flow rate and its distribution between spout and annulus, the liquid phase viscosity (water and carboxymethyl cellulose solutions), and the solid holdup (glass and cyclodextrin polymer beads) on the oxygen transfer efficiency were discussed. The oxygen transfer coefficient increased with the air flow rate and the ratio of air flowing through the annulus, whereas it decreased with increasing viscosity and solid holdup. A correlation was proposed to predict the transfer coefficient in DTSB reactors with primary and auxiliary aeration. A good fitting was achieved between the experimental data and those estimated with the model.