RHS in amorphous phase with 98% purity was prepared by leaching rice husk with HCl acid and calcination, and used as silica source for the synthesis of zeolite NaY. The NaY in pure phase was obtained from two-step synthetic route in which starting gels were mixed, aged for 24 h at room temperature and crystallized for 24 h at 90 o C. The diameter of single crystal from a scanning electron microscope was approximately 0.6-1.0 µm, whereas the average diameter of zeolite particles from the laser diffraction particle size analyzer was approximately 10 µm. When the crystallization time was longer than 24 h, NaY slowly transformed to zeolite NaP.