A new two-dimensional fluorinated gallium phosphate RbGa3(PO4)2(HPO4)F4·C5N2H16·2H2O (MIL-145) has been hydrothermally synthesized (180 °C for 36 h) in the presence of 1,5-diaminopentane and rubidium fluoride. Its structural model has been determined by means of single-crystal X-ray diffraction analysis. The structure contains corrugated infinite ribbons of GaO3F3 and GaO4F2 octahedra linked through edge- and corner-sharing mode via fluoride anions. These chains are then connected to each other via phosphate groups to create a layered network delimiting 6-ring channels trapping rubidium cations. The inorganic sheets are intercalated by diprotonated 1,5-diaminopentane and water molecules, ensuring the three-dimensional cohesion via hydrogen bond scheme. 1H, 13C, 15N and 87Rb solid-state NMR spectra show the presence of two inequivalent amines as well as two Rb cations, confirming the choice of the space group, which was ambiguous from the diffraction data. 71Ga NMR spectra, acquired at several magnetic fields, contain two different sets of Ga signals, corresponding to the two types of gallium environments in the structure. One-dimensional 19F and 31P and 19F–31P two-dimensional NMR experiments have been recorded, which are in full agreement with the proposed structural model. Finally, possible assignments of the 19F and 31P resonances to the crystallographic sites in RbGa3(PO4)2(HPO4)F4·C5N2H16·2H2O have been determined by comparing adjacency matrices build-up from 2D NMR correlation spectra and from the structural data.