Novel fluorinated copolymers of different architectures and bearing sulfopropyl groups were synthesized by atom transfer radical polymerization (ATRP) of aromatic fluorinated monomers and two modification reactions performed on the polymer chain - demethylation followed by sulfopropylation. As a result two types of fluorinated copolymers were obtained. The first one was synthesized by ATRP of2,3,5,6-tetraflouro4- methoxystyrene (TFMS). Copolymers with different amounts of randomly distributed along the backbone sulfopropyl groups were obtained after the chemical modifications mentioned above. The second type copolymers have diblock architecture with one.of the blocks being sulfopropyl~ed. They were synthesized via ATRP of 2,3,4,5,6pentafluorostyrene (FS) initiated by PTFMS-macroinitiator followed by demethylation and sulfopropylation performed on the TFMS-block (Scheme 1). The) copolymers were characterized by size-exclusion chromatography, FTIR and IH NMR spectroscopy. Their thermal properties were investigated by differential scanning calorimetry and thermal gravimetric analyses.