The synthesis of NiO/ZrO2 sulfated catalysts prepared by the one pot method (sol-gel) is reported. Specific surface areas comprised between 52 and 108 m(2)/g were obtained. XRD patterns showed the presence of monoclinic and tetragonal zirconia phases. FTIR-pyridine absorption spectra show the presence of Lewis and Bronsted sites in sulfated zirconia but only Lewis sites in nickel zirconia sulfated catalysts. A good correlation between the amount of adsorbed pyridine and the catalytic activity for the isopropanol dehydration was observed. However, an opposite effect was observed for the isobutene oligomerization, where the catalysts with the lower acidity showed the higher activity. The role of Ni+2 diminishing the deactivation rate forming pi-allylic bonds with the olefins is discussed. (c) 2007 Elsevier B.V. All rights reserved.