Plasma treatment has been increasingly used for surface cleaning, activation and polymerisation in many industries. In this study, the oxygen plasma treatment was used to remove the organic size from the ceramic fiber surface. The size removal from the fiber surface was characterized using an environmental scanning electron microscope. The combination of electron microanalysis and energy-dispersive X-ray allowed the observation of the fibre surface and the determination of the change in elements on the fiber surface. The use of low energy plasmas has been shown to be effective in the removal of the organic size from the ceramic fiber surfaces. It has also been revealed that the ESEM is a useful tool for surface characterization. (C) 2003 Elsevier B.V. All rights reserved.