The flow pattern and the distribution of energy dissipation rate in a batch rotor-stator mixer have been investigated. Sliding mesh and standard k-epsilon turbulence model were employed to predict velocity and energy dissipation rate distributions verified experimentally by the Laser Doppler Anemometry measurements. The agreement between predicted and measured bulk flow field as well as the flow pattern of jets emerging from the stator holes was very good. Results showed that the periodicity of the jet can be related to the rotor's velocity and number of blades. The energy balance based on measured velocity distribution indicated that about 70% of energy is dissipated in close proximity to the mixing head. Both simulation and measurement showed that the jet velocity and flowrate through the holes were proportional to N while the energy dissipation rate scaled with N-3. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.