A harmless and high-efficiency decomposition treatment for halogenized compounds using an electron source with a carbon nanotube has been proposed. Halogenized compounds such as PCB, chlorophenol, and dioxins contain some amount of chlorine. As the chlorine content is increased, a highly poisonous dioxin is produced. It is observed that the amount of high-concentration chlorophenol can be significantly decreased by using electrons with a carbon nanotube. The decomposition rate is ascertained to be approximately 100% for a 2 min treatment. The treatment with carbon nanotube is also effective for low-concentration halogenized compounds. (c) 2006 Elsevier B.V. All rights reserved.