The present invention relates to a coating method by electrocatalyzed chemical grafting of a surface of a substrate with a polymeric layer characterized in that it comprises the following steps: a. a substrate is provided, b. a bath containing at least one polymerizable monomer via a radical route, at least one cleavable aryl salt, at least one reducing agent and at least one solvent is provided, in which a potential difference is applied, c. said substrate is immersed in said bath, d. a grafted polymer is obtained on the surface of said substrate. The invention also relates to a substrate obtained according to the coating method by electrocatalyzed chemical grafting, the surface of which is coated with a polymeric layer.