This invention relates to a method for preparing an organic film at the surface of a solid support, with a step of contacting said surface with a liquid solution including (i) at least one solvent, (ii) at least one adhesion primer, under non-electrochemical conditions, and allowing the formation of radical entities based on the adhesion primer. The liquid solution can also include (iii) at least one monomer different from the adhesion primer and radically polymerizable. This invention also relates to a non-electrically-conductive solid support on which an organic film according to said method is grafted, and a kit for preparing an essentially polymeric organic film at the surface of a solid support.