Copper oxide is considered as an alternative electrode material for supercapacitors due to its low cost, chemical stability and high theoretical specific capacitance. In the present work, nanostructured copper oxide (CuO) films are prepared by radio-frequency (RF) magnetron sputtering, and the influence of the substrate temperature on the microstructure and supercapacitive properties was studied. The copper oxide films prepared at 350 °C exhibit a predominant ($\overline{1}$11) orientation corresponding to the monoclinic Cu(II)O phase with a crystallite size of 24 nm. The surface of the film consists of uniformly distributed oval-like grains providing a high surface roughness of 45 nm. The films exhibit an optical bandgap of 1.68 ± 0.01 eV and an electrical conductivity of 0.4 S cm⁻¹ at room temperature. The as-prepared CuO films deliver a discharge specific capacitance of 387 mF cm⁻² (375 F g⁻¹) at a current density of 1 mA cm⁻² with excellent cyclic capacitance retention of 95% (367 mF cm⁻²) even after 1000 cycles. Hence, these films are potential electrodes for micro-supercapacitors.