Axial mixing in the continuous phase of a 150 mm diameter Wirz-II extraction column has been investigated for six different liquid systems of low to medium interfacial tension with water as the continuous phase. The results were interpreted in terms of an empirical equation which allows for the physical properties, agitator speed, and flow rates, and predicts the axial mixing coefficient with an average absolute value of the relative deviation of less than 15%. Single-phase axial mixing was also studied and an equation obtained which predicts the axial mixing coefficient in terms of the agitator speed, continuous-phase velocity, and column geometry with an average error of 11%.