The growth of polyoxyphenylene coatings consisting of either a single copolymer layer or two homopolymer layers has been studied by electrochemical and x-ray photoelectron spectroscopy techniques. The composition of the coatings near the outer (coating/electrolyte) and inner (metal/coating) surfaces has been compared with the following results : (i) the inner face of copolymer coatings is enriched in the faster diffusing monomer; (ii) the inner and outer surfaces of coatings obtained by successive electrolyses of two different monomers are enriched in the second and first monomer, respectively. These results agree with a growth mechanism involving polymerization at the metal/coating interface controlled by monomer diffusion.