colloidal silica was modified by cerium ion to improve its polishing performance. The active silicic acid was mixed with cerium ion and was then titrated into the seed solution for surface modification via surface growth process. According to the experimental results, we found that the additional cerium ion can improve the surface growing ability on the seed (colloidal silica) surface. The particles size of cerium modified colloidal silica is larger than that without cerium modification. The mean particle size of the modified colloidal silica is decreased by increasing the seed concentration. The removal rate Of SiO2 of the modified colloidal silica is higher than that of without cerium modification colloidal silica. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.