The optimal location of one and two impellers on the central shaft of a tall stirred tank was obtained using a combination of Evolutionary Programing (EP) and Computational Fluid Dynamics (CFD) techniques; this location was evaluated through the determination of the normalized mixing time (T-N) and power consumption (Pc). The systems were simulated using 45 degrees pitched, down-pumping, 4-blade turbine impellers (PBT). The EP method considered a small population of 6 individuals (systems) where the impeller(s) were located on the shaft in order to cover most of the search space through the fitness function. Populations were generated by applying the selection and mutation of genetic operators to the best individuals for the next generation. Four generations of population were needed to find the optimal location of the impeller(s) in the shaft. The results show the best individual performance for the systems with one and two impellers. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.