A CMP composition having: a fluid comprising water and at least one oxidizing compound that produces free radicals when contacted with an activator; and a plurality of particles having a surface and comprising at least one activator selected from ions or compounds of Cu, Fe, Mn, Ti, or mixtures thereof disposed on said surface, wherein at least a portion of said surface comprises a stabilizer. Preferred activators are selected from inorganic oxygen-containing compounds of B, W, Al, and P, for example borate, tungstate, aluminate, and phosphate. The activators are preferably ions of Cu or Fe. Surprisingly, as little as 0.2 ppm and 12 ppm of activator is useful, if the activator-containing particles are suspended in the fluid as a slurry. Advantageously, certain organic acids, and especially dihydroxy enolic acids, are included in an amount less than about 4000 ppm. Advantageously, activator is coated onto abrasive particles after the particles have been coated with stabilizer.