 Single-crystalline (NH4)2V3O8 nanoflakes were successfully synthesized by a facile hydrothermal method. We investigated their electrochemical performance for use in lithium ion batteries for the first time. Interestingly, the as-prepared (NH4)2V3O8 electrode demonstrated good lithium storage properties. This material exhibited a high initial discharge capacity of 261.4 mAh g−1 at a current density of 150 mA g−1. Apart from the capacity loss in the first two cycles, the discharge capacity remained relatively stable and a capacity of 215.8 mAh g−1 was maintained after 30 cycles, indicating good cycling stability. The Coulombic efficiency was close to 100 % during the cycling, revealing that the intercalation/deintercalation of Li ions in this material was highly reversible. The good electrochemical performance of (NH4)2V3O8 was mainly attributed to its flake-like morphology and intrinsically stable layered structure.