The graft polymerization of vinyl monomers initiated by the system consisting of Mo(CO)(6) and trichloroacetyl groups introduced onto ultrafine silica, titanium oxide, and carbon black was investigated. The introduction of trichloroacetyl groups onto these surfaces was readily achieved by use of trichloroacetyl isocyanate. It was found that the polymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and glycidyl methacrylate is successfully initiated by the system consisting of Mo(CO)(6) and surface trichloroacetyl groups introduced onto these surfaces. In the polymerization, the corresponding polymers were effectively grafted onto these surfaces, based on the propagation of polymer from surface radicals formed by the interaction of trichloroacetyl groups and Mo(CO)(6): the percentage of polyMMA grafting onto silica, titanium oxide, and carbon black reached to 744,1, 150.5, and 35.4%, respectively. These values were extremely larger than that obtained from the radical graft polymerization initiated by surface azo and peroxyester groups introduced onto these surfaces. Polymer-grafted silica gave a stable colloidal dispersion in good solvents for grafted polymer.