NaX molecular sieve films on ceramic paper prepared by in-situ hydrothermal method were investigated. The NaX zeolite seed crystals of a uniform size of 5 µm were synthesized by hydrothermal method in a mother solution having a composition of 3.5Na2O : Al2O3 : 2.1SiO2 : 500 ~ 1000 H2O. These dip-coated NaX seed crystals on ceramic paper lead to further the thickness (20 ~ 100 µm) of NaX film on the substrate at 90°C for longer 3~7 days in autoclave. Pure zeolite films consisting of a continuous intergrown of 5~ 20 µm NaX crystal have been prepared on the substrates. The zeolite films were characterized by XRD, SEM, BET and XRF.