Newly dispersed Zr oxides on SiO 2 were prepared from Cp 2 ZrCl 2 , [(i-PrCp) 2 ZrH(μ-H)] 2 , and Zr(OEt) 4 precursors and were characterized by X-ray absorption fine structure (XAFS) and catalytic ketonization of acetic acid. ZrCp 2 Cl 2 and [(i-PrCp) 2 ZrH(μ-H)] 2 precursors yielded monomeric Zr oxides with unsaturated coordination in low loadings, whereas Zr(OEt) 4 yielded Zr-oxide assemblies in octahedral symmetry independent of Zr loading up to 15 wt% Zr. The former catalysts were more active than the latter catalyst for ketonization of acetic acid. The catalytic ketonization was suggested to proceed via bidentate acetates adsorbed on neighboring Zr sites.