A model of chemical mechanical polishing (CMP), based on a steady-state balance between chemical growth kinetics for a surface film and its mechanical removal rates, is extended to include the effects of inhibitors on the polishing rate. The general case provides qualitative insights into the process and presents a quantitative measure of inhibitor effectiveness. The model is applied to the case of tungsten CMP, with modifications in some details based on the complexity of the tungsten oxide surface film. The model is used to interpret data for three inhibitors in four slurry formulations and to explain their qualitatively different behaviors. (C) 2003 The Electrochemical Society.