Developing high-capacity cathode material is still a big challenge for room temperature Na-ion batteries. Herein, NaV6O15 nanoflakes are synthesized by a facile two-step method, in which (NH4)(0.5)V2O5 nanoflakes are first achieved by a hydrothermal approach and then transferred to NaV6O15 by a solid state reaction. The as-prepared materials are well characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). When used as a cathode for Na-ion battery, the NaV6O15 electrode exhibits good electrochemical performance with a high initial discharge capacity of 147.7 mAh g(-1) at 15 mA g(-1) and a capacity retention of 92.2% after 30 cycles during 1.5 similar to 4.0 V. The good electrochemical properties of NaV6O15 nanoflakes are mainly due to their rigid structure and stable two-dimensional nanoflake morphology. (C) 2014 The Electrochemical Society. All rights reserved.