Chemical dehydrohalogenation of poly(ethylene-alt-chlorotrifluoroethylene) (PE-a-CTFE) has been studied as a possible route to carbyne. The reaction products have been characterized by infrared and C-13 solid-state nuclear magnetic resonance spectroscopy. The dehydrohalogenation of PE-a-CTFE by potassium tert-butoxide in tetrahydrofuran has been shown to result in the formation of a halogen-substituted polyenyne structure with randomly distributed isolated triple bonds. The incomplete elimination of hydrogen halides can be explained by insufficient strength of the base, sterical hindrances caused by its bulkiness as well as by alternation defects in the original copolymer.