Malodorous gases give discomfort and harm to laborers and residential neighborhoods and therefore, the removing odor materials emitted from plants and industrial facilities is important subject. The main ingredients of alkali odor are NH₃ and CH₃SH. The adsorption characteristics of odors were studied using four different activated carbon fibers(ACF) and active carbon(AC). Alkali odor was removed by using ACF impregnated with H₃PO₄ and H₂SO₄ and treated with HNO₃ and NaOH. The experimental result showed that ACF has a higher removal efficiency than AC. The adsorption capacity was increased with the impregnation and surface treatment, and H₂SO₄ was the best impregnant for the removal of alkali odor.