AbstractThe use of electropolymerization to coat metal electrode surfaces with polymers formedin situwas investigated in detail. Electrolysis was carried out in a three‐compartment cell with fritted disk separators such that polymerization occurred in the middle compartment only. Both anodic and cathodic reactions were utilized to form coating on pretreated metal surfaces. It was shown that polymerization occurred both by vinyl polymerization of olefin monomers as well as by ring‐opening reactions of cyclic monomers. The factors that control the coating thickness, the morphology of the polymer deposit, and the adhesion of the polymer formed to the metal substrates were determined. It was found that the growth of the coating on electrode followed the chain polymerization kinetics to a considerable degree. However, increased current did not necessarily lead to increased coating thickness because it also led to increased early termination of growing polymer chains to form soluble low molecular weight products. Water, because of its high surface tension, encourages physical adsorption on metal surfaces of organic monomers dissolved in it. Thus, water was found to be unique as solvent for obtaining coatings with good adhesion to metal substrates. Coatings formed were analyzed by several methods including infrared spectroscopy. Several types of bonding, other than bond formation caused by polymerization reactions, were identified. Finally, the cyclization of polyacrylonitrile was observed when the coating was obtained on aluminum cathode during electrolysis of acrylonitrile–sodium nitrate–DMF s