The effect of Al content on the performance of the Pd-S2O82-/ZrO2-Al2O3 solid superacid catalyst was studied using n-pentane isomerization as a probe reaction. The catalysts were also characterized by X-ray diffraction (XRD), Fourier transform Infrared (FTIR), specific surface area measurements (BET), thermogravimetry-differential thermal analysis (TG-DTA), H-2-temperature programmed reduction (TPR) and NH3 temperature-programmed desorption (NH3-TPD). The Pd-S2O82-/ZrO2-Al2O3 catalyst made from Al2O3 mass fraction of 2.5% exhibited the best performance and its catalytic activity increased by 44.0% compared with Pd-S2O82-/ZrO2. The isopentane yield reached 64.3% at a temperature of 238 degrees C, a reaction pressure of 2.0 MPa, a space velocity of 1.0 h(-1) and a H-2/n-pentane molar ratio of 4.0. No obvious catalyst deactivation was observed within 100 h. (C) 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.