Pure-silica zeolites consistently display a strong hydrophobic character, but its exact extent can depend on the synthesis conditions of the material. Zeosils are typically obtained through hydrothermal synthesis 41 using fluoride (F -) or hydroxide (HO -) anions. Patarin and co-workers highlighted that the intrusion pressure of water was higher for silicalite-1 (F -) than for silicalite-1 (OH -), differing by 20 MPa. This shift of intrusion pressure may be attributed to the presence of internal defect in the framework, as silicalite-1 synthesized through the hydroxide route is known to contain more defects than using the fluoride route. Recently, it has been shown that intrusion of NaCl electrolyte solution in chabazite occurs in two steps: first only water molecules penetrate into the nanocages at 44 MPa, followed by intrusion of the ions at ∼260 MPa. The Rietveld analysis of the high-pressure phase revealed that the Na + cation interacts with the oxygen atom of the framework, while the Cl -anion is very close to the silanol defects. This motivated the present work where we investigate several models of silicalite and chabazite containing point defects, in order to probe their influence on electrolyte intrusion in the zeosils.