Ferroelectric ceramic fiber is expected to demonstrate a wide variety of practical applications in industrial fields due to the flexibility and shape anisotropy. Lead-free ferroelectric (Na,K) NbO3 (NKN) fiber was synthesized through electrospinning method using aqueous-based citrate precursor (CP). The morphology of electrospun fibers was observed and the properties of the precursor solution, such as viscosity, electrical conductivity and evaporation rate, were investigated. Addition of ethanol and acetic acid to the solvent of the PVA solution worked well for the electrospinning since both additives could control the electrical conductivity as well as evaporation rate of the CP/PVA prepared solution. The properties of the precursor, especially electrical conductivity and evaporation rate have significant influence on the morphology and homogeneity of the developed fibers. The homogeneous NKN fibers with a single perovskite structure of orthorhombic phase at room temperature and controllable diameter ranging approximately 100 to 1100nm were obtained, indicating that the electrospinning of ferroelectric NKN fiber through CP route was successfully conducted. (C) 2015 The Ceramic Society of Japan. All rights reserved.