Coal being a complex macromolecular solid is insoluble in most organic solvents. For structural studies, coal has to be subjected to chemical degradation to generate smaller fragments, which are more amenable for characterisation. For this, oxidative degradation is commonly used. A large number of wet oxidising agents have been used by researchers. All these oxidising agents have shown different reactivities and mode of attack with respect to coal. However, for structural analysis to be successful the fragments generated by oxidation must be well characterised to generate the maximum information. This review discusses the use of various instrumental techniques used to characterise the oxidation products.