Is a systematination of the synthesis of aluminophosphates possible? A step away from trial and error syntheses is permitted by an investigation of the link between the structure of aluminophosphate hydrates and the structure of the predominant species in the gel precursor. The ratio Al(O)/Al(T), i.e., the ratio of octahedrally to tetrahedrally coordinated aluminum, depends on the pH of the gel precursor. Thus, it is demonstrated that the crystallization reaction can be directed to the desired aluminophosphate phase simply by controlling the gel precursor pH.