The study of 4‐vinylpyridine belongs to an experimental approach developed since the 80sin our laboratory, which consists in studying the ability of vinylic monomers to form under cathodic polarization (in a strictly controlled aprotic medium) high quality films, grafted and polymerized onto a metallic electrode. The electropolymerization of 4‐vinylpyridine was studied as a function of the monomer concentration in the electrolytic medium made of an aprotic polar solvent: acetonitrile, and supporting salts. During the electropolymerization performed under cyclic voltammetry, an adsorption pre‐peak on the I=f(V) curves, corresponding to the polymer formation on the electrode surface, only appears for high monomer concentrations. In fact, the best experimental conditions required to build a poly (4‐vinylpyridine) film were obtained when using an electrochemical medium made of pure monomer and supporting salts. Under cathodic polarization, anionic polymerization of 4‐vinyl pyridine is then able to develop and to lead to the formation, on the electrode surface, of a grafted (and so, insoluble) poly (4‐vinylpyridine) film, which appears chemically pure. Finally, the structure of the polymer on the electrode was characterized by IRRAS (infrared absorption reflexion spectroscopy) and XPS (X ray photoelectron spectroscopy) and was compared with the standard polymer structure. ©1996 American Institute of Physics.