The effect of stator geometry on the flow pattern and energy dissipation rate in a batch rotor-stator mixer has been investigated using sliding mesh method with standard k-epsilon turbulence model. It has been found that for the stators with narrow openings (small width-to-depth ratio) the liquid at certain distance from stator rotated in the opposite direction to the rotor rotation. This opposite rotation was induced by the strong circulation flows behind the jets. The predicted power numbers for the stators with circular and square openings were about 10% lower than experimental data and the power number for stator with slot openings was about 20% lower. The simulation results showed that the power number was proportional to the total flowrate. For all stators, about 50-60% of energy supplied by the rotor dissipared in the rotor swept region and approximately 25% in the jet region. The fraction of energy dissipated in the hole region was 12-15% for stators with narrow opening and only 8% for stator with wide opening. The order of magnitude of energy dissipation rate in each region (rotor swept region, holes and jets) was practically the same for all stators; however, the distribution of energy dissipation rate in the hole was more uniform in stator with narrow openings. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.