Abstract: Two kinds of activated carbon fibers (ACF) made from polyacrylonitrile were selected in order to study their NO reduction properties. Experimental results showed that the NO reduction activity of HNO ₃ dipped ACF is higher than that of non-treated one. In order to know the adsorption properties of various oxygen containing gases on ACFs, TPD experiments over ACF showed that the adsorption abilities of CO, NO and O ₂ on HNO ₃ dipped ACFs are higher than that on non-dipped ACFs, but CO ₂ has a reverse result. According to literature and experimental results, we suppose that dissociative adsorption of NO on ACF is the rate controlling step of this reaction, and the primary product of this reaction is carbon dioxide.On the basis of this assumption, a first order kinetic equation was used to treat experimental data, and Arrhenius equations for NO reduction over four different ACFs were obtained.NO reduction activity of HNO ₃ dipped ACF was always higher than that of non-dipped one.