A series of gamma-Al2O3-supported SO42-/ZrO2 superacid catalysts (named SZ/Al2O3) were prepared by a precipitation method and their catalytic behavior for n-butane isomerization at low temperature in the absence of H-2 and at high temperature in the presence of H-2 was studied in this paper. The catalytic activities of some of these catalysts were enhanced significantly at both low and high temperatures. At 250(degrees)C after 6 h on stream, the steady activity of the most active sample, 60%SZ/Al2O3, is about two times higher than that of conventional SZ. The texture properties of catalysts were studied by the methods of XRD and the adsorption of N-2. Experimental evidence of IR of adsorbed pyridine indicates that the significant activity enhancements of SZ/Al2O3 catalysts are caused by the increasing of the amount of strong acid sites.