Mesoporous Ni(OH)₂ was synthesized using cationic surfactant as template and urea as hydrolysis-controlling agent. Mesoporous NiO with centralized pore size distribution was obtained by calcining Ni(OH)₂ at different temperatures. The BET specific surface area reaches 477.7 m²•g^－1 for NiO calcined at 523 K. Structure characterizations indicate the polycrystalline pore wall of mesoporous nickel oxide. The pore-formation mechanism is also deduced to be quasi-reverse micelle mechanism. Cyclic voltammetry shows the good capacitive behavior of these NiO samples due to its unique mesoporous structure when using large amount of NiO to fabricate electrode. Com-pared with NiO prepared by dip-coating and cathodic precipitation methods, this mesoporous NiO with controlled pore structure can be used in much larger amount to fabricate the electrode and still maintains high specific capacitance and good capacitive behavior.

Key words: mesopore, nickel oxide, electrochemical capacitor, pseudocapacitance