Inter-phase forces in a stirred bubble tank were studied through CFD method. The magnitudes of the drag force, the virtual mass force and the lift force in the tank were calculated. The flow velocities and gas hold-up profiles in the tank were simulated with integration of the virtual mass and the lift force in the model. The results from the simulation were tested with published experimental results. The prediction results showed that the lift force contribution was negligible. The lift force all over the tank was much smaller than the drag force and the virtual mass force. The virtual mass force was not negligible in the region near the impeller fringes. The virtual mass force reached its maximum in the sparger region and its magnitude was smaller than that of the drag force. The simulation results with incorporation of the virtual mass force and the lift force showed better prediction of gas hold profiles in certain areas of the tank than that without consideration of the virtual mass and the lift force. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.