Electrosorption is a novel desalination technique that has many advantages in the treatment of sewage. However, commercially available activated carbon electrodes for electrosorption commonly have low microporosity, poor molding performance, and low adsorption and regeneration efficiency. Here we evaluated a novel adsorbent material, activated carbon fiber felt (ACFF), for electrosorption of chromium ions (Cr6+) in sewage treatment. The ACFF was modified with 20% nitric acid and its modified structure was characterized. The modified ACFF was used as an adsorbing electrode to investigate its desalination effect by electrosorption. Results showed that compared with those of unmodified ACFF, the modified ACFF had more carbonyl and carboxyl groups and the specific surface area, average pore size and micropore volume of the modified ACFF also improved by 32.2%, 2.5%, and 23.1%, respectively. The kinetics of Cr6+ adsorption conformed to the pseudo-second order kinetic equation, and the adsorption isotherm conformed to the Langmuir model. In addition, the regeneration rate of the modified ACFF electrode was more than 94%. In conclusion, the modified ACFF exhibits excellent electrosorption and regeneration performance for Cr6+ removal from water and thus is of great value for promotion in sewage treatment.