Seven novel open-framework uranyl germanates, K-2(UO2)GeO4, K-6(UO2)(3)Ge8O22, alpha-Cs-2(UO2)Ge2O6, Cs-2(UO2)Ge2O6, Cs-2(UO2)GeO4, and A(UO2)(3)(Ge2O7)(2) (A = [NaK6Cl](6+), [Na2Cs6Cl2](6+)), were grown from different mixed molten fluxes. The three-dimensional (3D) structure of K-2(UO2)-GeO4 with 8-ring channels can be built upon [UGe4] pentamer secondary building units (SBUs). The 3D framework of K-6(UO2)(3)Ge8O22 with trapezoid (Ge8O22)(12-) clusters consists of two types of [UGe4] pentamers. The 3D framework of alpha-Cs-2(UO2)Ge2O6 with 10-ring channels, crystallizing in the P2(1)/n space group, is constructed by [UGe4] pentamers. The structure of beta-Cs-2(UO2)Ge2O6 contains achter (eight) single germanate chains and is composed of [UGe6] heptamers and [UGe4] pentamers. The structure of Cs-2(UO2)GeO4 with hexagonal 10-ring channels is composed of [U3Ge4] heptamers and twisting five-fold GeO4 tetrahedra in four-membered Ge4O12 rings occur. 3D frameworks of NaK6Cl(UO2)(3)(Ge2O7)2 (space group Pnnm) and Na2Cs6Cl2(UO2)(3)(Ge2O7)(2) (P2(1)/c) can be constructed from the same SBUs [UGe4] pentamers. Thermal stability of saltinclusions was studied by TG and PXRD analysis. Analysis of charge density for the U-Si-O system indicates that the polymerization of silicate units reduces the cross-links of the 3D frameworks. The concept of SBUs combined with the cutting and gluing strategy was applied to understand and analyze the distinct 8-, 10-, 12-, and 14-membered channels for the uranyl germanate family. The charge density of all known 3D U-Si/Ge-O frameworks has been investigated, which shows strong correlations with chemical composition of corresponding phases. The increase of Si/O (Ge/O) ratios in silicate units results in the decrease of negative charge density. Moreover, the charge density increases with decreasing countercation size within the same Si/O ratio. The correlations can be used to predict inclusion phase formation within U-Si/Ge-O families. Raman spectra of the studied uranyl germanates were measured, and bands were assigned on the basis of structural features.