A facile chemical precipitation method is used to prepare both lanthanum hydroxide [La(OH)(3)] and neodymium hydroxide [Nd(OH)(3)] nanopowders in an ambient temperature without the addition of any surfactants. Both rare-earth hydroxides nanopowders are characterized by X-ray diffraction and FE-SEM analysis. The supercapacitor performances of La(OH)(3) and Nd(OH)(3) electrodes are studied by cyclic voltammetry, electrochemical AC-impedance and galvanostatic charge-discharge studies. It revealed that Nd(OH)(3) electrode possesses a high specific capacitance (C-sp) than La(OH)(3) electrode. Hence, an asymmetric supercapacitor device is fabricated and denoted as Nd(OH)(3)parallel to AC in 6 M KOH as the electrolyte soaked in the electrospun poly(vinylidene fluoride) membrane as the separator, which exhibited an energy density of 18.8 Wh kg(-1) at a power density of 796 W kg(-1).