Abstract Dehydrochlorination (DHC) is of importance for modulating the physical properties of halogenated polymers. In this work, the DHC of commercial VDF‐CTFE (vinylidene fluoride‐co‐chlorotrifluoroethylene) (10 mol % CTFE) copolymer to VDF‐DB (vinylidene fluoride with unsaturated moieties‐ D ouble B ond) was achieved in mild reaction conditions (150 °C and 3 bar hydrogen) using different supported nickel catalysts. A complete DHC was observed within four hours of the reaction. Additionally, a certain extent (8–35 %) of hydrodefluorination (HDF) of the polymer, a challenging transformation, can also be achieved after 72 hours. A plausible mechanism based on the nuclear magnetic resonance (NMR) spectroscopy study of DHC and HDF of VDF‐CTFE was proposed. The catalyst was recyclable and stable against leaching after at least three cycles.