Global hydrodynamic characteristics, liquid mixing and gas-liquid mass transfer for a 63 L split-rectangular airlift reactor were studied. Correlations for gas holdup and overall liquid circulation velocity were derived for the air-water system as a function of the specific power input; these were compared to data and correlations for reactor volumes between 4.7 L and 4600 L. A partial recirculation of small bubbles in the riser was observed when U-gr > 0.03 m/s, which was attributed to the use of a single-orifice nozzle as the gas phase distributor. The dimensionless mixing time and the overall axial dispersion coefficient were nearly constant for the range of gas flow rates studied. However, values of K-L/d(B) were greater than those reported in previous studies and this is caused by the partial recirculation of the gas phase in the riser. While scale effects remain slight, the use of a gas distributor favouring this partial recirculation seems adequate for mass transfer in split-rectangular airlift reactors.