A three-dimensional CFD model has been developed to predict liquid phase velocities in bubble columns. An agreement was observed between the predicted and the experimental data available in the published literature. The validated CFD model has been extended for the simulation of macro-mixing and hence the prediction of mixing time, RTD and dispersion coefficient. Liquid phase mixing time was measured in 0.2 and 0.4 m i.d. columns over a wide range of superficial gas velocity (0.07 to 0.295 m/s) and height-to-diameter ratio (2 to 10). An agreement was observed between the CFD predictions and the experimental values of the mixing time as well as all the experimental data on dispersion coefficient published in the literature.