Using a green and effective method based on the solid state reaction between FePO4·2H2O and KBH4, high pure Fe2P nanoparticles are successfully prepared. The mass ratio of FePO4·2H2O to KBH4 has a decisive influence on the composition of the products. Moreover, Fe2P nanoparticles exhibit considerably high discharge capacities and excellent rate capability as the anode materials for nickel-based rechargeable batteries. The reversible discharge capacities are 413 and 343 mAh g−1 at currents of 100 and 500 mA g−1, respectively. It is expected that Fe2P nanoparticles have potential applications in nickel-based rechargeable batteries.