A novel template-free method to synthesize NiO microstructures is reported and the electrochemical properties of the fabricated microstructures are evaluated. Applying hexamethylenetetramine hydrolysis under a refluxing condition for 2h, α-Ni(OH)2 microstructures were synthesized, subsequent calcination at 300°C yielded NiO microstructures that retained the morphologies of their predecessors. The fabricated NiO microstructures had high specific surface area, large pore volume, and narrow pore size distribution making them ideal candidates for supercapacitor applications. The NiO microstructures have the high specific capacitance and displayed a good retention for more than 1000 cycles in a cycling test. The results suggest that NiO microstructures are a promising supercapacitor electrode material.