Supported MnOx nanocluster was prepared by PVP-stabilized Mn colloid as a precursor. Obtained catalysts were applied for 1-phenylethanol oxidation to produce acetophenone. Consequently, prepared catalysts were active for the oxidation of 1-phenylethanol using molecular oxygen without any additives such as base reagents. XAFS and TEM measurements revealed that the valence of manganese oxide and cluster size of manganese oxide on prepared catalysts can be controlled. In addition, the chemical state of Mn species varied with the loading amount of Mn.