The focus of this research was on the structure, reactivity and selectivity of γ-alumina, zirconia and their mixed oxides. These composites were prepared by means of sol-gel method using aluminum iso-propoxide and zirconyl nitrate precursors. The characterization of physicochemical properties was carried out using XRD, BET, TGA, SEM, FT-IR, and UV spectroscopy. Evaluation of catalytic activity and selectivity for dehydration of 2-octanol and 1,2-diphenyl-2-propanol (DPP) was investigated. Lewis acidity of Al and Zr sites was examined by the adsorption energy of water and 2-butanol over the (100) and (110) surfaces with the aid of density functional theory (DFT) at BLYP level of calculation. Adsorption of primary, secondary, and tertiary alcohols over (100) surface of defect spinel γ-alumina was investigated. The effects of alkyl, aryl, allyl and cyclohexyl substitutions were analyzed for free and adsorbed alcohols to shed light to the chemoselectivity of molecular adsorption of alcohols over γ-alumina surface. The mechanism of dehydration, dehydrogenation, ether formation, hydrogen-shift, and the conformational analysis of adsorbed (R)- and (S)-2-butanol over the (100) surface of γ-alumina was computed. The transition state models for the E2 dehydration reaction over the (100) surface of γ-alumina, E2 and E1cb dehydration reactions over the (110) surface of zirconia and Al doped zirconia was simulated. These results indicated that aromatic alcohols adsorb stronger than aliphatic alcohols and tertiary alcohols adsorb stronger than secondary and primary alcohols over the catalyst surface. This behavior was responsible for the high conversion of DPP vs. 2-octanol over pure catalysts. The crystalline 50% composite selectively dehydrated the tertiary alcohol (DPP) in presence of 2-octanol producing the E-2-alkene, while the amorphous 50% mixed oxide produced the 1-alkene.