Hydrothermal LiFePO4 has been successfully synthesized using iron powder as an iron source and as an in situ reducing agent. The 100% atom economy delivered by iron metal (Fe0) makes this process green and inexpensive. A plausible mechanism for the formation of hydrothermal LiFePO4 powder is also proposed. The structure of the LiFePO4 powder is well characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. The discharge capacity of the LiFePO4 electrode is found to be 165mAhg−1 at 0.1 C-rate, and the cycle-life performance is comparable to the conventionally synthesized LiFePO4.