The liquid-lift bioreactor is conceptually similar to the familiar air-lift bioreactor. A liquid is sparged into the base of a column containing a second, immiscible liquid of higher density. The two phases rise cocurrently to the top of the column, where they are separated. The dense phase is then recycled to the base of the riser, whereas the light phase is removed from the bioreactor. The hydrodynamic characteristics of a 12 L, liquid-lift, external-loop bioreactor have been investigated using water and oleic acid as the continuous and dispersed phases, respectively. The experimental unit had a working height of 1.7 m and a downcomer to riser area ratio of 0.43. A spinning sparger consisting of six, 1 mm diameter orifices spread evenly on a 4.4 cm diameter circle was incorporated near the base of the riser to allow for enhanced control of the produced droplets. Experimental studies were undertaken at superficial dispersed-phase velocities up to 4 cm/min and sparger spinning speeds up to 350 rpm (maximum orifice tangential velocity of 0.8 m/s). Uniform droplets were produced at diameters ranging from 1 to 5 mm, while liquid holdups and circulation velocities reached up to 2% and 3 cm/s, respectively. The droplet size data were best fit to an empirical model, and the well-known drift-flux theory of Zuber and Findlay was used to predict the dispersed-phase holdup. The circulation velocity of the continuous phase was predicted using an energy balance around the loop. The model was found to provide reasonable predictions of droplet diameter, dispersed phase holdup, and circulation velocity as functions of both the dispersed-phase superficial velocity and the spinning speed of the sparger.