The flooding behavior of an aqueous two-phase system was investigated using a laboratory-scale counter-current agitated Kuhni-type column. Experimental flooding limits were compared to the literature which has been established for aqueous-organic two-phase systems. Although the density difference and interfacial tension in the aqueous two-phase system studied were beyond the values typically encountered in aqueous-organic systems, comparison to the existing literature allowed for a prediction of the onset of flooding. Thus existing estimation procedures of the mean Sauter droplet diameter and terminal droplet velocity can be applied to aqueous two-phase systems. (c) 2013 Elsevier Ltd. All rights reserved.