The term zeolite is based on Greek words for “to boil” and “stone” and it is already known since more than 250 years. At that time, the Swedish mineralogist A.F. Cronstedt (1722-1765) observed the formation of large amount of steam when heating the material Stilbite pointing to his porous character and adsorption capacity. At present, over 200 different zeolite frameworks have been identified. In general, zeolites are crystalline aluminosilicates with defined micropore structure. Within zeolites, a good number of elements can be isomorphously incorporated and much more elements or their oxides can be hosted by zeolites. Besides their big variety in size of pore mouths, channels, crossings etc. leading also to their designation as molecular sieves and uses in membrane applications, zeolites reveal Brønsted and Lewis acidic properties that can be varied in wide limits as well. Thus, they deserve the name “solid acids”. Zeolites have an immense importance in diverse industrial applications as catalysts and adsorbents, for example in refinery industry, chemical industry, detergent sector or for solar thermal collectors and adsorption refrigeration In this special issue we aim at new developments and recent progress with respect to zeolite-catalyzed chemical reactions, adsorption applications and membrane uses as well as improved syntheses strategies and characterization techniques.