Microreactors based on zeolites and related materials are one of the latest developments in the field which started with the use of crystalline aluminosilicates for catalysis in the 1960s. These crystalline materials are highly thermally and hydrothermally stable, the number and strength of their acid sites can be conrolled, they have a high adsorption capacity, and contain channels of molecular dimensions, properties of interest for a number of applications. The history of the field is traced and a number of new applications of these materials is reviewed.