The effect of the support nature on the dispersion, structure, and catalytic activity of iron oxides supported on ZrO2, TiO2, ZnO, Al2O3, and silicas of different structures has been analyzed using the example of benzene benzylation. The structure and electronic properties of the catalysts prepared from iron acetylacetonate have been studied by Mossbauer spectroscopy. It has been shown that the use of SiO2, ZrO2, and ZnO supports characterized by weak oxide-oxide interaction leads to the formation of small iron oxide clusters of a 2-10 nm size, which exhibit the highest activity in catalysis.