Many processes in the fine chemical industry, by consisting in liquid phase organic reactions, use transition metal salts or complexes as homogeneous Lewis acid catalysts due to the coordination capacity of metals in dissolution, with the consequent problems in the recovery of products, being the use of solid catalysts an operational advantage. Solid Lewis acid catalysts potentially active and selective in typical acid-base reactions, and redox type processes also, can be obtained trough the incorporation of metallic species with vacancies in their coordination environment on adequately selected inorganic matrix. In this doctoral thesis a series of solid Lewis acid catalysts have been developed, in which the metallic active centres are isolated and distributed homogeneously (“single site catalysts”). The Lewis acidity of these catalysts have permitted to carry out a large range of oxidation reactions, including olefin epoxidations and MPV-O type oxidations, as well as the oxidation of sulfides to sulfones. In all the cases, it has been tried to deepen in the knowledge of the reactions and to elucidate the physical-chemical interactions of the substrates with the catalyst. With these bases, we have carried out a rational design of the catalyst for every one of the different cases studied, in order to extrapolate the know-how to processes of industrial interest, with the purpose to solve existing problems in the field of the fine chemistry.