In this work, the cubic polymorph of (NH 4 ) 3 FeF 6 has been obtained at room temperature via a precipitation reaction within 2min by a phase-transfer method. The structural properties of the sample were investigated by X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). This is the very first time to report that iron-based fluoride has been prepared without using hydrofluoric acid or at high temperature, and give an application of (NH 4 ) 3 FeF 6 as a novel anode material for lithium-ion batteries. (NH 4 ) 3 FeF 6 exhibits decent first discharge and reversible specific capacities of 1035mAhg −1 and 555mAhg −1 at room temperature, respectively.