the invention relates to a method of cleaning the surface of a material that is coated with an organic substance . the inventive method is characterised in that it comprises the following steps , consisting in : introducing the material into a treatment chamber , having a pressure of between 10 mbar and 1 bar therein , which is supplied with a gas stream containing at least 90 volume percent of oxygen ; and generating a plasma by passing an electric discharge between the surface of the material and a dielectric - covered electrode in order to break down the organic substance under the action of the free radicals o thus produced . the invention also relates to an installation that is used to carry out said method .