Four new organically templated uranium(IV) phosphates, (C 4 H 16 N 3 )[U 2 F 3 (PO 4 ) 2 (HPO 4 )] ( 1), (C 6 H 21 N 4 )[U 2 F 4 (PO 4 )(HPO 4 ) 2 ] (2), (C 4 H 16 N 3 ) 2 [U 2 F 10 (HPO 4 ) 2 ] (3), and (C 6 H 16 N 2 ) 2 (UF 7 )(H 2 PO 4 ) (4), have been successfully synthesized in pure-phase form under mild solvothermal conditions and characterized by single-crystal X-ray diffraction, magnetic susceptibility, thermogravimetric analysis (TGA), elemental analysis, inductively coupled plasma-atomic emission spectroscopy, and fluorine analysis. They are the first tetravalent uranium phosphates with encapsulated organic templates ever reported. All four materials display unique dimer-structured topologies with various dimensionalities in the inorganic/hydrogen-bonded networks. In this series, U 4+ ions are located in the center of bicapped trigonal prisms of UFO 7 , UF 2 O 6 , UF 6 O 2 , or UF 8 , from which edge-sharing U 2 F m O 14-m dimers (m ) 2 and 4 in 1, m ) 4 in 2, m ) 10 in 3, and m )14 in 4) are formed. The less-fluorinated U 2 F 2 O 12 and U 2 F 4 O 10 dimers are connected to eight and six phosphate groups to give two-dimensional layer and one-dimensional chain structures, respectively; the more-fluorinated U 2 F 10 O 4 and fully fluorinated U 2 F 14 dimers are respectively attached by two or zero phosphate groups to form clustered structures. TGA results indicated that the layered structure of 1 could sustain heating up to ∼300 °C and the thermal stability of the series steadily decreased with decreasing structural dimensionality. The 4+ oxidation state of uranium was confirmed by bond-valence-sum calculations and magnetic susceptibility measurements. In view of radioactive mobility, we discovered that 1 and 2 could be more stable than UO 2 under sufficiently oxidizing conditions. Crystal data: triclinic, space group P1 j , a ) 9.1657( 4) Å, b ) 10.0618(4) Å, c ) 10.7584(4) Å, R ) 73.668(1)°, β ) 65.366(1)°, γ ) 65.916(1)°, and Z ) 2 for 1; monoclinic, P2 1 /c, a ) 11.1124(4) Å, b ) 19.6830(8) Å, c ) 10.1466(4) Å, β ) 114.362(1)°, and Z ) 4 for 2; monoclinic, space group P2 1 /n, a ) 18.383(1) Å, b ) 7.8448(6) Å, c ) 18.442(1) Å, β ) 113.967(1)°, and Z ) 4 for 3; monoclinic, P2 1 /c, a ) 10.2346(9) Å, b ) 23.846(2) Å, c ) 8.8091(8) Å, β ) 93.459(2)°, and Z ) 4 for 4.