The ability to manipulate the morphology and structure of core-shell materials on a micro/nano scale can further control their physical and chemical properties, leading to the wider applications. Herein, the conventional electroless deposition technique for metal alloy films on solid substrates was adapted to synthesize the Ni-P micro/nano-composites in solution under high temperature and high pressure through the hydrothermal method. The obtained amorphous Ni-P composites exhibit perfect roundness with the multilayer structure of concentric circle. By controlling the erosion condition in HNO3, the special embryo-like structure was obtained where a solid microsphere is encircled by a layer of hollow globular ultrathin film with the thickness smaller than 50 nm. A round hole opens on the surface of the embryolike structure. The reaction or formation mechanism was tentatively discussed. The methods can be used to produce the special micro-/nano-structures of metal phosphide. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.