The rheological properties and conductivities of three different bentonite clay sludges in varying concentrations by volume have been determined. The KCl salt and (NaPO3)(n) polymer which were added to samples of the sludge in seven different concentrations had different effects on the viscosity, yield point and conductivity values. These differences observed were related to different ways in which the salt and the polymer interact with the negatively charged clay particles. The results show that the eta(a) and tau(y) values are directly related to concentration by volume of the clay in the sludge and inversely related to the conductivity values. The effect of KCl on the viscosities of the three different sludge samples with varying concentration is similar. The (NaPO3)(n) polymer, contrary to KCl salt, reduces the rheological values of the sludges. In the use of the bentonite clay sludges in industry, the addition of the (NaPO3)(n) polymer is recommended whenever an decrease in the viscosity of the sludge is necessary; and the addition of KCl salt is recommended if an increase in viscosity is desired.