Elemental carbon is produced by chemical dehalogenation of perfluorinated hydrocarbons at room temperature and pressure. This method allows pre-paration of unstable carbyne-like materials, which can be subsequently converted to carbon nanotubes. Direct chemical carbonization of 1,3,5-hexatriyne derivatives also leads to nanotubes. Total dehalogenation of perfluorocyclo-pentene, perfluoronaphthalene and perfluorodecalin produces C-60 (fullerene) in ca. 0.01-0.1% yield and about 1-2% of carbon nanotubes and onions. Precise thin carbon films were also grown by chemical dehalogenation of various perfluorinated hydrocarbons.