The technological characteristics of a bentonite supplied from Kütahya region were determined by chemical analysis, differential thermal analysis, particle size analysis and x-ray diffraction techniques. The bentonite containing calcium montmorillonite and illite as clay minerals and also a-cristobalite, a non clay mineral was treated thermally between 100°C-1300°C. The changes in the adsorptive properties, such as the specific surface area and specific pore volume, under the effect of thermal treatment temperature, which are determined by the adsorption and desorption of nitrogen at 77K, were discussed. The bentonite was activated by the “wet process” with sulfuric acid at various acid ratios from 10% to 70% in add and clay mixture. The dependency of adsorptive properties of the bentonite on the add ratio by the activation procedure was discussed