The chemical conversion of the top surface of 3-glycidoxypropyldimethylethoxysilane (GPDMES) on hyroxylated silicon surface has been studied as a function of reaction time. A multiple-step procedure was applied in this study. At first, GPDMES molecules were self-assembled on the hydroxylated silicon surface. The second step was the modification of epoxy groups with 3,3'-iminodipropionitrile and the last step was the amidoximation reaction of nitrile groups. Existence of the monolayers covalently attached to silicon surfaces were revealed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Modification, conversion and thickness of surfaces were followed by FT-IR and ellipsometry analysis. (C) 2012 Elsevier B.V. All rights reserved.