In a method of synthesizing an aluminophosphate or silicoaluminophosphate molecular sieve, a synthesis mixture is prepared by mixing a plurality of starting materials including at least a source of water, a source of phosphorus, a source of aluminum, optionally, a source of silicon and, and at least one organic directing agent for directing the formation of said molecular sieve. The starting materials are maintained at a temperature between 25.degree. C. and 50.degree. C., preferably between 30.degree. C. and 45.degree. C., during the mixing and until preparation of the starting mixture is complete, whereafter the synthesis mixture is heated to a crystallization temperature between about 100.degree. C. and about 350.degree. C. until crystals of the molecular sieve are produced. When crystallization is complete, the molecular sieve is recovered.