The present invention provides a composition for chemical-mechanical polishing which comprises at least one abrasive particle having a surface at least partially coated by a activator. The activator comprises a metal other than a metal of Group 4(b), Group 5(b) or Group 6(b). The composition further comprises at least one oxidizing agent. The composition is believed to be effective by virtue of the interaction between the activator coated on the surface of the abrasive particles and the oxidizing agent, at the activator surface, to form free radicals. The invention further provides a method that employs the composition in the polishing of a feature or layer, such as a metal film, on a substrate surface. The invention additionally provides a substrate produced this method.