Abstract: Crystalline aluminosilicates having a high (greater than 10:1) silica to alumina molar ratio and an X-ray diffraction pattern substantially the same as that of ZSM-5 zeolite are prepared by mixing a source of silica, a source of alumina, a source of alkali metal, water and at least one monoalkanolamine selected from monoethanolamine and monopropanolamine or their precursors, the ratio of the source of silica to the source of alumina being at least 20:1 based on the equivalent moles of silica and alumina in their respective sources, and maintaining the mixture at a temperature of about 120.degree. C. or 135.degree. C. or more for a time such that crystallization occurs. Typical crystallization conditions are a temperature in the range 120.degree. to 210.degree. C., a pressure in the range from autogenous to 400 psig and a time not less than 4 hours and up to and in excess of 7 days.