CuS nanosheets and their various assembled forms prepared by dealloying a Ti-Cu amorphous alloy have been investigated as electrochemical pseudocapacitor materials for energy storage applications. The properties of the assembled forms of the CuS nanosheets are determined by using the concentration of H2SO4 employed in the dealloying process. Spherical clusters composed of CuS nanosheets were fabricated by this process. These clusters have the highest specific surface areas provided by the nanosheets and exhibit high electrochemical and charge storage-release performances. The CuS spherical clusters showed a high specific capacitance of ∼276Fg−1 (at a scan rate of 5mVs−1 in cyclic voltammetry tests) and ∼713Fg−1 (at a charge-discharge current of 1.0Ag−1). The high pseudocapacitive performance can be attributed to the highest specific surface area in our case and absence of volume change of the nanosheets. These results suggest the importance of a rational nanostructure design for high-performance energy applications.