Using X-ray powder diffraction analysis, Al-27 and P-31 magic angle spinning nuclear magnetic resonance, and nitrogen adsorption-desorption, it has been shown that, during the crystallization of AlPO4-11 and SAPO-11 molecular sieves, the use of pseudoboehmite as an aluminum source leads to the formation of intermediate phases, which are crystalline aluminophosphates AlPO4 center dot 2H(2)O and isostructural silicoaluminophosphates with a mesoporous structure.