Methyl orange (MO) was employed to evaluate degradation efficiency of the synergistic effect of activated carbon fibers (ACFs) and pulsed discharge non-thermal plasma in aqueous solution. In order to study the roles of the ACFs during the degradation activities, adsorption-catalytic effects of ACF samples modified with H2O2, Fe(NO3)(3) and steam were assessed. The chemical and physical properties of these ACFs were characterized by XRD, SEM, BET and chemical titration methods. For comparative purposes, experiments of adsorption on ACF samples, plasma degradation, and plasma degradation in the presence of ACF samples were carried out. Plasma alone can obtain the decoloration of 77.3% for 100 mg/L MO solution and generate H2O2 (0.88 mM) and O-3 (0.025 mM) after 30 min treatment. Results also showed that the presence of either ACF(0) or modified ACFs considerably improved MO decoloration and COD removal in the plasma reactor. Compared with ACF(0) and ACF-H2O2, a total decoloration of MO and above 90% COD removal were obtained in approximately 30 min for ACF-steam and ACF-Fe(NO3)(3) due to their larger adsorption capacities and better catalytic effects. In combined degradation processes, the yields of H2O2 and O-3 all decreased in presence of ACF samples as compared with plasma alone process. It was also observed that ACF samples can be well regenerated in combined processes and their adsorption behaviors contributed little for final organic removal. (C) 2012 Elsevier B.V. All rights reserved.