An electrochemical deposition coating method was developed to encapsulate submicrometer sized silica particles with nanosized CuO particles. The particle size of the as-synthesized CuO particles was estimated to be below 10 nm from X-ray powder diffraction and transmission electron microscopy (TEM). The thickness of the coating layer measured using TEM ranged from a few nanometers to about 20 nm. The optical absorption spectrum exhibited evidence of formation of CuO nanocrystals with dimensions on the order of a few nanometers as a result of the quantum confinement effect. Zeta potential analysis also proved the presence of CuO coating layer and full surface coverage of the silica particles. (C) 2003 The Electrochemical Society.