THE BACKGROUND: Earth atmosphere contains 12,900 km³ of moisture available regardless of geographical and climatic conditions. Furthermore, it is estimated that the natural hydrological cycle generates an abundant reserve of humidity globally. Therefore, atmospheric humidity can be considered as a rich renewable source of fresh water, the availability of which constitutes a possible answer to the problems of clean water supply, a problem which currently affects 2.2 billion people, a number which unfortunately is increasing due to the gradual desertification of some regions of the world. The need for new freshwater provision approaches, has become a critical issue worldwide. Up until now, the most common approach, to produce it, is by exploiting brackish or sea water sources which must be desalinated. Such process is characterized by a high energy consumption and is not green due to the production of wastewater at high temperature and high salt concentration.

In this scenario MOFs come into play thanks to their high flexibility in both structural and chemical functionality, their structural and physico-chemical properties, i.e. high specific surface, pore size and shape, hydrophilicity, MOFs can be used in different boundary conditions. Furthermore, they can be regenerated at low temperatures, and they present a promising water-sorption capacity.