A transparent, activated, nonparticulate alumina with a total porosity of about 63% which consists of a unique pore morphology and size distribution and is thermally stable up to about 1200.degree.C. at which temperature it can be nondestructively converted to alpha alumina is disclosed as well as a method of preparing said alumina by hydrolyzing aluminum alkoxides to form a particular sol which is essentially clear to the naked eye and the gel of which retains its integrity during drying and pyrolysis. The alumina thus produced is useful as a catalyst, absorbent and desiccant. In addition, a method of preparing the intermediate clear colloidal sol or gel consisting essentially of aluminum monohydrate is disclosed. This intermediate can be used to coat various substrates.