Sulfated zirconium clays were prepared by adding ammonium sulfate to the intercalation solution. The main controlled parameter in this study is the SO4:Zr ratio in solution. The characterization of these catalysts, their acidic properties and their catalytic activities was examined by N-2-BET adsorption, chemical analysis, the adsorption-desorption of basic molecules, the conversion of n-hexane and the transformation of isopropanol. Two different types of SO4-Zr polycation binding were advanced and correlated with the acidic properties of these solids. To enhance the acidity of the sulfated zirconium clay, the SO4:Zr molar ratio must be up than 0.125. The higher this ratio, the higher is the activity of these solids. It appears that highly polymerized entities are more active than individual sulfated polycations. The isopropanol dehydration to propene as well as the isomerization of n-hexane seems to be related to the number and the strength of Bronsted acidity. (C) 2004 Published by Elsevier B.V.