An amorphous MnO 1.9 thin film was deposited by magnetron sputtering with manganese as the target. The morphology and structure of the deposited MnO 1.9 thin film were investigated. The MnO 1.9 thin film presented amorphous structure in X-ray diffraction measurement. In transmission electron microscopy, it was revealed that the MnO 1.9 particles distributed homogenously on the copper substrate and the diameters of particles were less than 10nm. The cyclic voltammetry and galvanostatical discharge–charge curves indicated that the MnO 1.9 thin film had regular capacitive behaviors and delivered a maximum capacitance of 50.2mF/cm 2 μm and 23.3mF/cm 2 μm under 0.1mA/cm 2 and 1.0mA/cm 2 current densities, which demonstrated that the amorphous MnO 1.9 thin film was a potential good electrode material for supercapacitor application.