In this work, the interaction between bentonite particles and the potassium chloride is studied. Several experimental measurements such as x-ray diffraction (XRD), zetametry, and rheology have been employed. The use of a controlled stress rheometer has enabled us to determine the rheological parameters (yield stress and elastic modulus) of bentonite suspensions (3 wt.%) in the presence of potassium chloride at various concentrations (0.05-6 wt.%). The results indicate that rheological parameters of bentonite suspension vary as a function of the concentration of electrolyte due to the structural change of the material studied. To highlight the effect of chloride potassium on the microstructure of bentonite suspensions, the basal distance (d(001)) of the montmorillonite was determined by XRD method. The zetametric measurements show that the zeta potential increases drastically for KCl concentrations beyond 0.5 wt.%. This leads to the destabilization of the water-bentonite-KCl system. Based on the test results, it is recommended to choose the optimum concentration of KCl in the bentonite suspension, to avoid the degradation of rheological parameters.