Newly dispersed Zr oxides on SiO2 were prepared from Cp(2)ZrCl(2), [(i-PrCp)(2)ZrH(mu-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)Zr(mu-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.