Sulfated-hafnia promoted zirconia containing various compositions of hafnia ( 1-10 wt.%) were prepared by precipitation method in an attempt to ultimately carry n-butane isomerization reaction. The catalyst samples were calcined under dry air flow at 600 degrees C. The structural and crystal changes were monitored by FUR and XRD whereas the textural changes were estimated by low temperature N-2 adsorption. Flu spectroscopy has been used to characterize the hydroxyl groups and to determine the concentration of Bronsted and Lewis acid sites from pyridine adsorption. The catalytic activity, stability and selectivity of the catalyst samples were tested for n-butane isomerization at 250 degrees C. The results reveal that the existence of a small content of hafnia increases the surface sulfate density, stabilizes the tetragonal phase of zirconia, increases the amount and strength of Bronsted acid sites and enhances the initial catalytic activity of the samples. Increasing hafnia content to 5 and 10 wt.% is accompanied with the formation of hafnia monoclinic phase which causes it drastic decrease in the amount of Bronsted acid sites and the initial activity of the catalyst. The isomerization of n-butane occurred through bimolecular pathway with the formation of iso-butane, propane and pentanes as primary products. In spite of the high activity of the samples, the catalyst deactivates rapidly during the first hour of the reaction due to coke formation, retreating the catalyst at 450 degrees C in the presence of dry air before the catalytic reaction lead to regeneration of the initial catalytic activity of the catalyst which implies that the coke formation is the main source for catalyst deactivation. (C) 2011 Elsevier B.V. All rights reserved.