Ga 3 (PO 4 ) 3 F 2 , 0.75 H 3 N(CH 2 ) 3 NH 3 , 0.5 H 3 O (ULM-4) was obtained by hydrothermal synthesis (453 K, 24 h, autogenous pressure) from a mixture of Ga 2 O 3 , H 3 PO 4 , HF, 1,3-diaminopropane and H 2 O in the ratio 1:2:2:1.3:80. The structure was studied by single-crystal X-ray diffraction and solid state NMR. It is monoclinic (space groupP 2 1 /n (no. 14)) with a=8.674(1) 9, b=10.190(2) 9, c=16.826(3) 9, β=94.21(2)°,V =1483.1(7) 9 3 and Z=4. The open framework delimits one-dimensional 10-ring channels; it is built up from the hexameric unit Ga 3 (PO 4 ) 3 F 2 in which the gallium atoms exhibit two types of surrounding. One of the three gallium atoms is octahedrally coordinated and the two others are in trigonal bipyramidal coordinations where fluorine atoms link the gallium atoms together. Strong hydrogen bonding interactions between the fluorine and the amine functions of the diamines are evidenced. The structure was examined by 3 1 P, 1 9 F, 1 5 N and 1 3 C solid-state nuclear magnetic resonance spectroscopy. Structural relationships with GaAsO 4 -2 are discussed.