Shuttle-shaped, porous copper oxide (CuO) microparticles were prepared from Cu(OH)2 in a water/cyclohexane interfacial reaction followed by heat treatments at different temperatures. The CuO catalysts produced high catalytic activity and good durability for hydrazine oxidation reaction (HOR). Among all catalysts, CuO catalyst heat treated at 200°C provided the highest HOR activity with an onset potential of -0.204 V and a high oxidation peak current density of 0.87 mA cm-2 of HOR. HOR performances of the CuO catalysts correlated to their porous structure and transition of different Cu species. These findings shed light on factors influencing HOR activity of CuO catalysts.