A chemical kinetics model was proposed to describe the abrasive size effect on chemical mechanical polishing (CMP). The model is based on the consideration of a pad as a sort of catalyst and the re-adhering of abrasives due to the large size. Therefore, a general equation was deduced according the chemical kinetics methodology to give the meanings of the size effect. Finally, according a set of data related to the abrasive size effect on CMP, a possible form can be PR = alpha CCCTXACWAn/[beta + gamma XACWAn] where alpha, beta, gamma and n are the parameters in a CMP system. (c) 2004 Elsevier B.V. All rights reserved.