The influence of the mixing parameters on the synthesis of Al-SiCp reinforced metal matrix composites (MMCs) by the stir casting technique is investigated through a water model. The effects of some important mixing parameters such as impeller blade angle, rotating speed, direction of impeller rotation and effect of baffles are investigated and optimized. The results have shown that the axial concentration variation of natural graphite during stirring in the presence of four vertical baffles is 1.0 wt% against in the absence of baffles it is increased to 2.3 wt%. The variations observed in natural graphite concentration in water during mixing are in close agreement with the earlier modeling and limited experimental studies reported on the real molten aluminum-SiC system. Semi-empirical correlations arrived at between the dimensionless numbers for stirred water - natural graphite slurries are Po = Re-0.0545 Fr-1.099 and Po = Re-0.0219 Fr-1.0382 for clockwise and counter clockwise rotation respectively. © 2005 Elsevier Ltd. All rights reserved.