A new hydroxonium iron phosphate, (H3O)[Fe(H2O)](3)[H-8(PO4)(6)] -3H(2)O, was synthesized through a precipitation route by means of acidic media. The crystal structure was solved by X-ray powder diffraction. Electrochemical characterizations, performed on this compound, show reversible intercalation of lithium and substantial lithium diffusion. Protonic conductivity is observed in agreement with the simultaneous presence of H2O, hydrated protons and OH groups in the large intersecting tunnels of this intersecting tunnel structure. (c) 2006 Elsevier B.V All rights reserved.