A mechanical flotation cell necessitates generation of three distinct hydrodynamic zones for effective flotation. The ratio between the height of turbulent and quiescent zones play a key role in cell efficiency. The effect of impeller speed and size, cell aspect ratio (height of the pulp to cell diameter) and superficial gas velocity on the height of turbulent and quiescent zones have been considered in other research. In this paper, the effect of cell cross section was investigated. The experiments were conducted in a cylindrical cell and two rectangular cells with different cross sections. Piezo electric sensor was applied to determine the height of the turbulent and quiescent zones. Turbulence conditions were changed by varying the impeller speed. In rectangular cells, the height of the turbulent and the quiescent zones was independent of the impeller speed while in the cylindrical cell the height of the turbulent zone increased by increasing the impeller speed. These results are practicable to optimize turbulence in mechanical flotation cells in order to reduce the entrainment and increase the true flotation.