The preparation of co-crystals via mechanochemistry combines the quest for clean and green processes with the investigation of multicomponent new materials, among the currently most fashionable systems in the crystal engineering field: the physico-chemical properties of the components add, merge or transform when co-crystals are formed, giving rise to potentially improved performance in "old" solid-state chemistry fields, as in the pharmaceutical industry field, where they represent a way to obtain new formulations and to improve the properties (solubility, thermal stability, compressibility, etc.) of both new and existing drugs.