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.