Here we report the rate capability and cycling stability of NaFePO4 in aqueous electrolyte at various temperatures and voltage windows and compare it to its performance in organic electrolyte under similar conditions. In aqueous electrolyte the polarization was strongly reduced, leading to superior capacity at all tested rates compared to organic electrolyte with a comparable voltage window. Moreover, by fine tuning the voltage window, the capacity retention was notably improved, indicating that this material is a good candidate for aqueous Na-ion batteries, which we have confirmed by reporting the cycling stability of a NaFePO4/NaTi2(PO4)(3) aqueous full cell. (C) 2015 Elsevier B.V. All rights reserved.