[en] Organic coatings synthesized using plasma techniques, often called plasma polymers, are very frequently characterized routinely using X-ray photoelectron spectroscopy. In this paper, we show that, due to the intrinsic chemistry and structure of plasma polymers, such characterization is not trivial and should be carefully driven. Some routes to improve the characterization are proposed, and we show also that XPS, combined with other gas phase or solid state characterization techniques can successfully help to improve the structure, chemistry, and polymerization process of the coatings.