The radical copolymerization of chlorotrifluoroethylene (CTFE) with 3,3,4,4-tetrafluoro-4-bromobut-1-ene (BTFB) initiated by tert-butylperoxypivalate is presented. The microstructures of the obtained copolymers are determined by means of NMR spectroscopies and elemental analysis and show that random copolymers were obtained. A wide range of poly(CTFE-co-BTFB) copolymers is synthesized, containing from 17 to 89 mol % of CTFE. In all the cases, CTFE is the less reactive of both comonomers. T-d(10%) values, ranging from 163 up to 359 degrees C, are dependent on the BTFB content. These variations of thermal property are attributed to the increase in the number of C-H and C-Br bonds breakdown when the BTFB molar percentage in the copolymer is higher. T-g values range from 19 to 39 degrees C and a decreasing trend is observed when increasing the amount of BTFB in the copolymer. This observation arises from the higher flexibility of the copolymer when increasing the number of fluorobrominated lateral chains. These original fluoropolymers bearing reactive pendant bromo groups are suitable candidates for various applications. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1714-1720