Mixed gamma-alumina and thorium oxide samples were prepared with various compositions (100, 95, 90, 80, 50, 25, 15, 5 and 0 wt%, respectively) by addition of a solution of thorium nitrate to a slurry solution of aluminum isopropoxide [Al(OC3H7)(3)] in deionized. water. Mixed oxides (slurry solution) were heated at 120 degrees C (oil bath) for 24 h with mixing (for uniform distribution of oxides and to remove excess water) followed by calcinations at 600 degrees C for 6h. New Fourier-transformed infrared spectroscopy (FTIR) absorption bands and the absence of crystallinity demonstrated by XRD analysis clearly show that gamma-alumina and thorium oxide are mixed chemically and on atomic scale during the calcination period. The mechanically mixed oxide retained crystallinity and do not show mixing on the atomic scale. The evaluation for the catalytic activity of single or the chemically mixed catalysts for the dehydration of 2-hexanol and 1,2-diphenyl-2-propanol was investigated. The infrared spectrum of gamma-alumina calculated by AM I method show absorption pattern similar to FTIR. (c) 2005 Elsevier B.V. All rights reserved.