A composition and associated method for chemical mechanical planarization (or other polishing) are described. The composition contains an abrasive, benzenesulfonic acid compound, a per-compound oxidizing agent, and water. The composition affords tunability of removal rates for metal, barrier layer materials, and dielectric layer materials in metal CMP processes. The composition is particularly useful in conjunction with the associated method for metal CMP applications (e.g., step 2 copper CMP processes).