Abstract A novel molybdenum phosphate based on [Mo6P4] inorganic subunits and [Mn(H2O)2]2+ cations, Mn[Mo6O12(OH)3(PO4)(HPO4)2(H2PO4)]2[Mn(H2O)2]2(Hen)4·13H2O (en = ethyl enediamine), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy, EPR spectrum and TGA analysis. The 3-D framework of the compound contains microporous structure with large cavities filled by mono-protonated Hen+ and water molecules. The electrochemical behavior of the compound has been also studied.