The synthesis and characterization of zeolite NaY nanocrystals (Nano-NaY) from Vietnamese kaolin have been carried out. Nano-NaY has been modified to Nano-USY and used as catalyst for the alkylation of benzene with isopropanol to obtain cumene. Nano-NaY has been succesfully synthesized with surface area of 565 m(2)/g (in which external surface area of (102 m(2)/g), crystal size of 22 nm, contains both micropores (of 0.81 nm) and mescipores (of 12 nm): The SiO2/Al2O3 ratio increases from 3.87 to 5.52 after the modification of Nano-NaY to Nano-USY.