Al-promoted mesostructured sulfated zirconia (Al-MSZ-5) has been successfully synthesized from the template of triblock polymer surfactant (P 123) in aqueous solution. Mesostructured Al-MSZ-5 shows high thermal stability, and it can preserve its characteristic mesostructures until calcination at 650degreesC. In contrast, the mesostructure of mesoporous sulfated zirconia (MSZ-5) will be destroyed during calcination at 600degreesC. Catalytic data for n-butane isomerization show that the Al-MSZ-5 exhibits higher catalytic activity and better stability than both MSZ-5 and conventional Al-promoted sulfated zirconia (Al-SZ). The Al-MSZ-5 sample was characterized by XRD, bright-field and dark-field TEM images, N-2 adsorption isotherms. NMR, TG-DTA, IR, and numerous other techniques. The results suggest that Al-MSZ-5 has worm-like mesopores. and that the mesostructured walls contain tetragonal crystalline ZrO2. Such unique structural features might be responsible for the observed large surface area. high catalytic activity for n-butane isomerization, and high thermal stability of mesostructured Al-MSZ-5. (C) 2004 Elsevier B.V. All rights reserved.