Porous carbon polyhedra (PCP) were prepared through direct carbonization of zeolitic imidazolate framework-8 and used as an electrode material for capacitive deionization. The results show that PCP treated at 1200 °C exhibit the highest electrosorption capacity of 13.86 mg g(-1) when the initial NaCl concentration is 500 mg l(-1), due to their high accessible surface area and low charge transfer resistance.