A new iron phosphate, KMgFe(PO4)(2) has been synthesized and investigated by X-ray diffraction, Mossbauer spectroscopy and ionic conductivity. This compound crystallizes in the monoclinic space group C2/c with the parameters a = 18.529(7) angstrom, b = 5.402(3) angstrom, c = 9.374(9) angstrom. beta = 120.64(5)degrees and Z = 4. Its original structure can be described as the stacking along the [101] direction of [MgFe(PO4)(2)(-)](infinity) layers of corner-sharing MO4 (M = 0.5 Fe + 0.5 Mg) and PO4 tetrahedra. The K+ ions are occupying the inter-layer space. The Mossbauer spectroscopy confirms the occurrence of only tetrahedral Fe3+ ions and gives a definitive proof of the disordered character of their distribution. Ionic conductivity results obtained by the impedance spectroscopy technique show that this material is a two-dimensional ionic conductor, with low activation energy, 0.51 eV, that is interpreted on the basis of two-dimensional pathways. (C) 2009 Elsevier B.V. All rights reserved.