Oxidant-free dehydrogenation of alcohols has attracted considerable attention, owing to the largely improved utility value of alcohols. Herein, mixed metal oxides (MMOs) via topological transformation of Mg-Al hydrotalcite precursors were prepared and used as support for the immobilization of metallic Ag nanoparticles. The resulting Ag/MgAl-MMO shows an excellent catalytic performance toward oxidant-free dehydrogenation of benzyl alcohol (conversion of benzyl alcohol: 95.9%; selectivity of benzaldehyde: 93.3%), which is close to platinum-group catalysts commonly used in this reaction. A combination study based on a series of characterization methods reveals a synergistic catalysis between Ag and medium-strong acid/basic sites (Mg delta+-O delta-) from support: Ag delta+ facilitates the breakage of alpha-C-H bond while Mg delta+-O delta- accelerates the cleavage of O-H bond. This work provides an effective approach to enhance catalytic behavior toward dehydrogenation reactions by virtue of metal-support interactions.