Abstract: Various superacid SO42-/ZrO2-Al2O3catalysts were prepared by a coprecipitation, and modified by aging at low temperature and addition of the rare earth oxide, such as La2O3. A optimum atomic ratio of Zr/Al was found to be 0.5, which was confirmed by the catalytic activity of samples forn-butane isomerization . IR measurements demonstrated that the intensity of the peak at 1393cm-1for the samples aged at low temperature and containing the rare earth oxide was more higher than that for the samples at room temperature. For the sample containing the RE oxide and aged at low temperature, XRD observed a metastable tetragonal phase of ZrO2crystal which is responsible for the higher catalysis activity as we believe. The observation of catalytic activity for esterification of sucrose further evidenced the conclusion mentioned above.