Non-zeolitic molecular sieves are prepared by contacting a body of alumina or silica-alumina (optionally containing reactive sources of phosphorus pentoxide and/or other elements desired in the non-zeolitic molecular sieve) with a liquid reaction mixture containing a reactive source of phosphorus pentoxide (and optionally reactive sources of silica and/or other elements desired in the non-zeolitic molecular sieve), and an organic templating agent, thereby causing the body to react with the liquid reaction mixture and to form crystals of the non-zeolitic molecular sieve within the body.