Abstract Two synthetic gallosilicates and a gallogermanate with the NAT, EDI and THO framework topologies have been synthesized under hydrothermal conditions and characterized by single crystal synchrotron X-ray diffraction. K-GaSi-NAT, K 8Ga 8Si 12O 40·6H 2O, is tetragonal, space group I 4 ̄ 2d, with a=13.639(2), c=6.545(1) Å. The framework model shows complete disordering of Ga and Si in tetrahedral sites, which is analogous to tetranatrolite but contrasts with the partial ordering in Na-GaSi-NAT. The T-sites of RbNa-GaSi-EDI, Rb 7NaGa 8Si 12O 40·3H 2O, exhibit partial disordering of Ga and Si in space group P 4 ̄ 2 1c. This leads to a cell doubling along the chain axis ( c) with a=9.773(1), c=13.141(3) Å, a super cell modification of the Na-exchanged K- F structure. In Rb-GaGe-THO, Rb 20Ga 20Ge 20O 80·15H 2O, a=14.335(3), b=14.198(3), c=13.421(3) Å, complete ordering on both tetrahedral and extra-framework sites lowers the symmetry from Pncn to the acentric space group Pn2 n. An inspection of framework TOT bond angles, which are related to rotation and distortion of the chains, explains the differences in unit cells between these gallium- and germanium-variants and aluminosilicate analogs. The elliptical 8-ring windows, generated by four crosslinked chains in RbNa-GaSi-EDI and Rb-GaGe-THO, are the sites for (Rb,Na) and Rb cations, respectively, while the helical 8-ring channels formed in K-GaSi-NAT host only water molecules. The T 10O 20 windows, built by two neighboring chains, provide sites for K or Rb cations in each model. Mechanisms are proposed for cation–framework interactions, which are in turn responsible for the observed framework models.