The volumetric overall mass transfer coefficients in a multistage column have been measured using axial dispersion model for toluene-acetone-water system. The effect of operating parameters on the volumetric overall mass transfer coefficients has been investigated for both mass transfer directions. The results show that the mass transfer performance is strongly dependent on rotor speed and mass transfer direction, although only slightly dependent on phase flow rates. In addition, empirical correlations to predict the overall mass transfer coefficients have been developed. The proposed correlations based on dimensionless numbers can be considered as a useful tool for the possible scale up of the multistage column extractor. (C) 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.