Abstract: The hierarchical nickel oxide microspheres with extended nanoflakes on Ni foam were prepared via microwave- assisted method with Ni(NO3)2 as the Ni source.The effect of the reaction time on the morphology and structure of the NiO spheres has also been investigated systematically.The microstructure and morphologies of the resulting materials were charac- terized by XRD，SEM，and TEM.Results indicated that reaction time had a large influence on the product′s structure and morphology.When the microwave power was 100 W，reaction time was 1.5 h and current density of electrode was 1 A/g，spe- cific capacitance of electrode reached 350 F/g and showed an excellent rate characteristics.

Key words: microwave method, nickel oxide microspheres, porosity, capacitance performance