Copper oxides nanosheets and nanowires were directly grown on a copper sheet by a single step voltammetry process in an alkaline solution. The transition from the out-of-plane nanosheets to high aspect ratio nanowires is triggered by the change in the voltage sweep rate. The scan rate changes the growth mechanism from nucleation and coarsening at the slow scan rate for nanosheets to an oriented oxide nanowire growth at high scan rates. Polycrystalline copper oxide nanostructures contain both Cu(I) and Cu(II) oxide phases, which were characterized by the FEG-SEM, XRD, XPS, Raman, and TEM analysis. The copper oxides nanosheets and nanowires electrodes delivered the maximum specific areal capacitance 320 mF cm−2, energy density 3.36 µWh cm−2 and, power density 1.7 mW cm−2 with capacitance retention of 115% up to 5000 cycles.