Porous materials are of great interest, both theoretically and experimentally, in various scientific and technical areas (micelles, sponges, rocks, construction materials, wood, biological materials, etc.). For this reason it is important to have at hand experimental techniques for a proper characterization of their physical properties. The most relevant characteristic parameters of porous materials are: porosity, distribution of pore sizes or, more precisely, the volume/surface ratio of the pores, permeability. NMR has been found a uniquely useful way of studying these characteristics by overcoming the opacity problem. NMR methods make it possible to directly investigate, in a non-destructive and non-invasive way, mass transport (fluids, gases) in pore matrices, pore matrix structures, as well as mass distribution inside pore systems. A number of NMR diffusometry applications, often accompanied by relaxometry, are applied in geophysics and hydrology (porous rocks, sediment and soil columns), civil engineering (construction materials such as concrete), chemical engineering (reaction and sorption columns, catalyst beds), biomedicine (bone, tendon, cartilage) etc.
