The hydrodynamic characteristics of the Maxblend (TM) impeller have been investigated in the case of viscous Newtonian fluids. Both laboratory experiments and 3D finite element based computational fluid dynamics (CFD) simulations have been carried out. The power consumption, the mixing evolution yielding the mixing time, and the effect of baffles in the laminar and transition flow regimes have been determined. It was found that the limit Reynolds number between the laminar and transition regimes is approximately 25 and 38 for the unbaffled and baffled configurations, respectively. Based on the range of Reynolds numbers studied in this work, the best window performance of the Maxblend (TM) mixer where fast and homogenous mixing is achieved is the end of the laminar regime and the early transition regime with baffles. (c) 2007 Elsevier Ltd. All rights reserved.