Arc in a vacuum was applied for surface cleaning of metal with organic contamination. At the time of the cleaning, the metal surface layer was molten and defected by vaporizing and quenched because of rapid heating and cooling caused by cathode spot motion, which resulted in surface change after the cleaning. The influence of contaminant density or discharge current on change of surface was experimentally investigated. It is revealed that the post-treatment surface condition strongly depends on both these factors. (c) 2005 Elsevier B.V. All rights reserved.