Adsorption and electrosorption of thiocyanate (SCN-) anions on active carbon felt electrodes were measured by UV spectroscopy and cyclic voltammetry to provide more knowledge of the application of electrosorption on high-area carbon material in industrial waste water purification. Positive polarization caused increased adsorption of SCN-. SCN- showed the highest electrosorption capacity at about pH 3. Reversible electrosorption of SCN- to different extents was observed by changing the direction of polarization currents, which is possibly accompanied by the accessible surface area of C-felt being increased by positive polarization and electrochemical oxidation of SCN-. The enhanced capacity for adsorption by positive polarization will improve reuse of active carbon felt. (c) 2005 Elsevier Inc. All rights reserved.