The Ni12P5 hollow nanocapsule structure is synthesized adopting a facile one-pot hydrothermal method without any templates. The size of the obtained Ni12P5 nanocapsules is about 20nm, and the wall thickness is about 3nm. The XPS spectra of Ni12P5 samples were measured to identify the surface chemical composition and valence states. Oxygen evolution reaction results show that the onset overpotential of Ni12P5 is 290mV and clearly demonstrates the Tafel slope of 49.8mVdec−1. Meanwhile, the Ni12P5 nanocapsules show excellent electrochemical properties with specific capacitance of 949Fg−1 at 1Ag−1 and 81% of the initial value after cycles. Excellent electrochemical performances demonstrate that the nickel phosphide from a facile synthesis strategy could be a candidate for high performance energy storage and conversion.