This webinar is proposed in French only. It highlights the growing importance of surface characterization in industry, where surface composition directly impacts material performance. Over the past decades, treatments and coatings have been widely developed to improve corrosion and oxidation resistance, reduce friction and wear, and enhance thermal, electrical, and aesthetic properties—making advanced analytical methods essential. Among these, Glow Discharge Optical Emission Spectrometry (GDOES) stands out as a powerful tool for analyzing oxide layers, corrosion products, and hydrogen embrittlement. It provides fast, multi-element analysis across varying layer thicknesses and works effectively on rough or contaminated industrial surfaces, while detecting nearly all elements, including light ones such as O, C, H, and N.