The analysis of sol-gel derived materials is a far from trivial task for two main reasons: the starting materials are very different from the final products (both chemically and physically), and secondly, due to the enormous versatility of the sol-gel method, the resulting materials (and their precursors) can cover a vast range of both physical and chemical properties. For example, the precursors are monomers and their reaction products polymers, the former generally are soluble, the latter insoluble. Further­ more, they may be hydrophobic vs. hydrophilic, liquid vs. solid, and during the process many intermediate stages are generated. The final products, however, may also be very different: they can be hydrophilic or hydrophobic, gels or glasses, films or bulk materials, inorganic or hybrid materials, dense or porous, tough or brittle. They can have various degrees of cross-linking and may be based on different metals such as silicon, titanium, vanadium and niobium, or mixtures of them. For these reasons a variety of chemical and physical characterisation techniques have been used to analyse the different aspects of these materials. The most important of these will be treated in this chapter. The chapter aims to convey the key features of the techniques with some representative examples, rather than attempting to give a comprehensive review of the contemporary literature in this vast area.