A novel preparation technique was developed to synthesize LiFePO4 nanoparticles through a combination of spray pyrolysis (SP) with wet ball-milling (WBM). Using this technique, the preparation of LiFePO4 nanoparticles was investigated for a wide range of process parameters such as ball-milling time and sintering temperature. The effect of process parameters on the physical and electrochemical properties of LiFePO4 was then discussed through analysis using by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), the Brunauer–Emmet–Teller (BET) method, Raman spectroscopy and using an electrochemical cell of Li|1M LiClO4 in EC:DEC=1:1|LiFePO4. LiFePO4 nanoparticles with a geometric mean diameter of 58nm were prepared at a rotating speed of 800rpm and a ball-milling time of 12h in an Ar atmosphere followed by heat treatment at 500°C for 4h in a N2 +3% H2 atmosphere. The sample delivered first discharge capacities of 164 and 100mAhg−1 at charge–discharge rates of 0.1 and 10C in the test cells, respectively. The electrochemical properties of LiFePO4 nanoparticles were strongly affected by the formation of Fe2P, Fe3P and α-Fe2O3 at higher charge–discharge rates.