Abstract: Recent developments on the capacitive deionization (CDI) technique for water desalination are reviewed with a focus on carbon as the electrode material. The capacity and rate of salt adsorption and charge efficiency of various types of CDI cells, i.e. flow-by, membrane, flow-through-electrode, and flowing electrode cells are compared. Various carbon electrode materials for capacitor-type and battery-type cells are discussed. The flowing electrode cell with the short-circuit operation mode seems to be the most promising one for practical applications.