Abstract: Method for the fluorination of a surface layer of articles molded from plastic, vulcanized rubber or other such macromolecular substances by the exposure of at least a part of the article's surface to a fluorine-yielding liquid in a controllable reaction, the liquid consisting of a solvent or solvent mixture containing dissolved elemental fluorine. Suitable solvents are especially halogen hydrocarbons in accordance with DIN 8962, which are liquid within a temperature range from -30.degree. C. to +10.degree. C., but also water and solvents having perfluoroalkyl groups. The liquid, in which a fluorine concentration between 0.5.times.10.sup.-3 and 1.times.10.sup.-2 mol/l is established by the introduction of fluorine diluted with inert gas, is used to treat the articles for about 20 seconds to 30 minutes; the fluorine can be activated if desired. The liquid can additionally contain sulfur dioxide, oxygen, carbon monoxide, chlorine, bromine, or mixtures thereof.