Titanium-oxo clusters are employed as inorganic nanobuilding blocks in order to obtain new organic-inorganic hybrid materials. Nanobuilding blocks are well-defined preformed entities which allow a better control of the inorganic domains for the elaboration of hybrid nanocomposites. The oxo-alcoxo cluster Ti16O16(OEt)32 presents a shell of labile ethoxy groups which can be selectively exchanged with preservation of the oxo-core. Both the kinetics of the solvolysis and the number of substituted titanium atoms are strongly dependent on the nature of the reactants. The post-modification of the cluster lead to the elaboration of new oxo-alcoxo clusters Ti16O16(OEt)32- x(OR)x (R : alkyl, phenyl… groups) and when polymerizable ligands, such as methacrylate or styrenic ligands, are introduced at the surface of the nanobrick, new functional nanobuilding blocks can be obtained. These functional clusters are then copolymerized with organic monomers leading to 3D networks where the inorganic nano-fillers are covalently linked to the organic polymer and act as very effective nano-cross-linker. These nanobricks can be considered as good models to correlate the structure of hybrid materials and their physical properties especially their mechanical, thermal, and optical properties.