Two new hybrid organic-inorganic molybdates based on layered 2/infinity[MonO3n+1](2-) blocks and organoammonium cations (+)(MexH3-xN)-(CH2)(6)(NH3-xMex)(+) (X = 0-1), namely, (H3N(CH2)(6)NH3)[Mo7O22]center dot H2O (I) and (MeH2N(CH2)(6)NH2Me)[Mo9O28] (2), have been synthesized under hydrothermal conditions. The 2/infinity[Mo9O28](2-) unit in 2 is an unprecedented member of the 2/infinity[MonO3n+1](2-) family with the n value extended to 9. The structural filiation between the 2/infinity[MonO3n+1](2-) (n = 5, 7, 9) blocks is well established, and their structural similarity with the 2/infinity[MoO3] slabs in alpha-MoO3 is also discussed. Single-crystal X-ray analyses show that the 2/infinity[MoO3n+1](2-) layers in 1 and 2 are pillared in the three-dimensional networks by the organic cations with a similar connection at the organic-inorganic interface. In addition, a correlation between the topology of the 2/infinity[MonO3n+1](2-) blocks in 1 and 2 and the overall sizes of the associated organic cations is pointed out. Finally, the efficiency of Fourier transform Raman spectroscopy to easily discriminate the different 2/infinity[MonO3n+1](2-) blocks (n = 5, 7, 9) in hybrid organic-inorganic layered molybdate materials is clearly evidenced.