Abstract: Composition for a coating protecting the surfaces of carbon-containing products exposed to a hot, oxidizing environment such as the parts of anodes not immersed in the molten salt bath and the liners of the aluminum electrolysis cells and more generally the non-immersed parts of carbon-containing refractory elements used in electrolysis conducted below 950.degree. C. in a molten salt bath, comprising a geopolymer, preferably in the fluoropoly(sialate-disiloxo) family, the other components possibly being water as well as alumina and/or a refractory other than silica. Coating protecting the surfaces of carbon-containing products exposed to a hot, oxidizing environment such as the non-immersed parts of carbon-containing refractory elements used in electrolysis conducted below 950.degree. C. in a molten salt bath, including polysilicates and at least one inorganic polymer in the poly(sialate) family, preferably fluoropoly(sialate-disiloxo), also possibly with alumina or another refractory other than silica.