Zeolite faujasite type with hexagonal structure (EMT) and zeolite faujasite types with cubic structure (FAU) were synthesized with crown ethers as templating agents. The Si/Al ratio of the as-synthesized samples was determined to 3.7. The samples were dealuminated by steaming at 773, 873 and 1073 K, respectively. A part of the dealuminated samples was treated with diluted acid to extract the non-framework aluminum. Nature and concentration of the acid centres were estimated by IR spectroscopy and TPDA measurements. From N-2 isotherms follows that the extracted samples undergo a partial damage of the structure. It seems that the EMT samples are more stable in the process of steaming and extraction with diluted acid.