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[Display omitted] • The In 2 O 3 +ZrO 2 physical mixture (PM) is much more active than its components. • PM generates isobutene at high selectivity while its components almost do not. • DRX and XPS showed that ZrO 2 promotes distortions in the In 2 O 3 lattice. • The distortions turn easier the generation of O vacancies during the reaction. • PM catalytic performance is associated with the facility of vacancies generation. A physical mixture comprising In 2 O 3 and ZrO 2 and its components were employed as catalysts in the generation of isobutene from ethanol. These solids were characterized by means of several techniques such as EPR, HRTEM, XPS, XRD, N 2 physical adsorption, isopropanol-TPD, CO 2 -TPD, ethanol-TPD and pyridine adsorption. The addition of 7% of In 2 O 3 to ZrO 2 employing the physical mixture procedure generates a catalyst which shows physicochemical and catalytic properties which are not a linear combination of its components properties. This catalyst is not only much more active compared with In 2 O 3 and ZrO 2 , but it also generates isobutene at high selectivity. The interaction between In 2 O 3 and ZrO 2 changes the quantity and strength of the acidic and basic sites. However, these modifications do not correlate with the catalytic behavior. The HRTEM data suggest that the epitaxy alignment occurs between these two oxides which might cause stresses in the In 2 O 3 lattice. The XRD and XPS analysis have identified distortions in the In 2 O 3 lattice provoked by ZrO 2 , which facilitate the generation of O vacancies and consequently increases the concentration of these species during the reaction. This phenomenon promotes the acetone and acetaldehyde syntheses which are very relevant intermediate of this cascade reaction. Thus, it can be suggested that the catalytic behavior of the modified physical mixture is associated with the In 2 O 3 lattice distortions promoted by ZrO 2. [ABSTRACT FROM AUTHOR]