Monodisperse colloidal silica with controlled sizes (100, 200 and 300 nm) has been prepared by the Stober process. The shape and monodispersity of the synthesized colloidal particles were observed by scanning electron microscopy and laser light scattering particle analyzer. Self-assembled monolayer (SAM) of monodisperse colloids was obtained by dipping a Si substrate into a well-dispersed silica suspension. It was found that the uniformity and spatial extent of colloidal SAM were significantly influenced by the experimental parameters such as concentration, pH and surface tension of the colloidal suspension. We have observed a hexagonally well-ordered packing colloidal monolayer in a relatively large area (1.5 X 1.5 mm(2)). The platinum was sputtered over the colloidal SAM used as a lithographic mask. This produced a honeycomb-shaped patterned Pt structure of thickness similar to60nm on the Si substrate after the removal of the colloidal silica. (C) 2003 Elsevier B.V. All rights reserved.