Recently, new methods for the introduction of fluorine-containing substituents into aromatic compounds have been developed in our Department and new types of organic substances synthesized. Emphasis has been placed not only on the 'classic' groups, such as the fluorine atom or perfluoro-aIkyl and -alkenyl fragments, but mainly on substituents with perfluoroalkyl groups separated from the nuclei by the heteroatoms oxygen, sulfur (in valency states 2, 4 and 6), nitrogen and metals. We have also developed new principles for the construction of super-strong electron-withdrawing substituents and superstrong acids. This approach consists in replacing the sp(2)-oxygen atom in various groups with the =NSO2CF3 radical and has been confirmed by examples of substituents with the central atoms consisting of sulfur in different valence states, carbon, phosphorus and iodine. From this principle, a stable substituent with sigma(p) constant 1.76, equal to three nitro groups in its influence toward benzene nuclei, has been constructed.