Potato starch and foamed Si, nanopowder were mixed in a planetary ball mill to study the cohesive powder flowability of the mixt. The effect of mixing time, mixing speed and SiO2 amount on flow indices (angle of repose, compressibility index) was detd. by using response surface methodology based on central composite rotatable design. The mechanochem. method of powders treatment was an efficient tool for improvement of cohesive powder flowability and the process optimization.