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Cu/Zn/Al mixed oxides catalysts were obtained from their corresponding layered precursors synthesized by coprecipitation of components varying M(II)/M(III) molar ratios of 2, 3, and 4 while maintaining Cu2+/Zn2+ molar ratio at 1.0. Crystalline phases concentration in the precursors was determined by Rietveld refinement analysis. Hydrotalcite (HTLc) phase concentration decreased from 79 to 32 wt % as M(II)/M(III) molar ratio increased from 2 to 4, respectively. A constant value of M(II)/M(III) molar ratio of 1.3–1.4 was determined for HTLc formation independently of the M(II)/M(III) molar ratio used for the synthesis. The excess of M(II), Cu and Zn components, segregate as Rosasite phase. Therefore, mixed oxides with different surface properties were obtained depending on the precursor crystalline phase component. Precursor with mainly HTLc phase generates mostly a homogenous Cu/Zn/Al mixed oxide where Al atoms hinder Cu reduction. On that sample no Cu0 was detected by XPS, then, hydrogen consumption during its reduction process was related to the presence of anionic vacancies, where H 2 can be heterolytically dissociated and stored in its hydric form, generating highly active hydro/dehydrogenation sites, with highest Lewis acidity. When the mixed oxides come from a precursor with mainly Rosasite phase, mixed oxides decompose into Cu0, ZnO, and Al 2 O 3 during reduction, where metallic Cu0 acts as dehydrogenating sites during ethanol dehydrogenation to acetaldehyde. In fact, higher Cu surface concentration favors the dehydrogenation route, increasing the yield towards acetaldehyde, whereas a high Al surface concentration enhances the dehydration path increasing diethyl ether yield. [Display omitted] • Cu/Zn/Al mixed oxides were obtained from layered precursors of HTLc and rosasite. • Surface properties of mixed oxide depend on the precursor composition. • Anionic vacancy sites are generated during reduction process. • Vacancies sites can dissociate H 2 and stored it. • Ethanol dehydrogenation to acetaldehyde occurs over vacancy sites. [ABSTRACT FROM AUTHOR]