Low-temperature ferroelectric G2 polymorph of K3WO3F3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K3WO3F3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3) angstrom, b = 8.6808(5) angstrom, c = 6.1581(3) angstrom, beta = 135.124(3) angstrom, V = 329.46(3) angstrom(3); R-B = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A(2)BMO(3)F(3) oxyfluorides is discussed. (C) 2010 Elsevier B.V. All rights reserved.