microporous material to reversibly take in molecules into its void volume (Fig. 1). For a material to be called microporous, it is generally necessary to demonstrate the gas sorption property. The report by Davis et al. of a hydrated aluminophosphate VPI-5 with pore size larger than 10Å in 1988 generated great enthusiasm toward the synthesis of extralarge pore materials . The expansion of the pore size is an important goal of the current research on microporous materials . Even though microporous materials include those with pore sizes between 10 to 20Å, The vast majority of known crystalline microporous materials have a pore size <10Å. The synthesis of microporous materials with pore size between 10 and 20Å is desirable for applications involving molecules in such size regime and remains a significant synthetic challenge today. In the following sections, we will first review oxide-based microporous materials followed by a review on related chalcogenides. We will then discuss metal-organic frameworks, in which the framework is a hybrid between inorganic and organic units. The research on metal-organic frameworks is a rapidly developing area. These metal-organic materials are being studied not only for their porosity, but also for other properties such as chirality and non-linear optical activity . The last section gives a discussion on materials with extra-large pore sizes. There exist many excellent reviews and books from which readers can find detailed information on various zeolite and phosphate topics [1,4,13,18,19,20,21,22,23,24,25].