The effect of interfacial properties on the characteristics of gas/liquid contacting achieved in tanks agitated by self-aerating Rushton-type impellers surrounded by a stator was investigated. As a consequence of concentrating energy dissipation rate in the small gap between the impeller and stator, large gas holdups (up to 0.19) and interfacial areas as high as 4160 m(2) m(-3) were obtained in slowly-coalescent systems. The results obtained also suggest that surface tension inadequately characterizes the effect additives have on the dynamic equilibrium be tween the individual processes of dispersion and coalescence.