Highly dispersed NaFeF3 particles were prepared at 280°C by liquid-phase synthesis using high-boiling-point organic solution, and their electrochemical properties were studied by charge and discharge measurements. TEM observation clarified that the resultant NaFeF3 particles had uniform particle sizes of ca. 10–20, 100–200, and 500–600nm, which could be controlled by the composition of the synthetic solution. The discharge capacities were higher for NaFeF3 that had smaller particle sizes, particularly at a rate of 0.1C or higher, while the discharge capacities obtained at a rate of 0.01C between 1.5 and 4.5V were almost the same in the range 170–181mAhg−1 regardless of the particle size of NaFeF3. These results clearly indicate that the use of well-dispersed nano-sized NaFeF3 particles should effectively improve the rate performance of NaFeF3.