Zeolites are molecular sieves that hold great importance in the field of catalysis, where they are used as (both) an active phase and/or a catalyst support. Here, we aim to study the interzeolite crystallization process of a FAU mixture to AEI, utilizing SAXS/WAXS techniques. As a result, engaging the studied mechanism, one can understand the evolution of AEI zeolite from crystalline Si and Al sources with the aim of optimizing the synthesis parameters to control the final Si/Al ratio of the product.