Zeolite ZSM-48 with a high crystallinity can be synthesized from a reaction mixture containing a silica source from rice husk gasification ash. For high crystallinity zeolites, the optical density ratio, A/B (a criterion for determining the structural characteristics of the zeolite frameworks), for ZSM-48 is equal to 0.25. The difference in the cracking behavior of n-hexane for zeolites ZSM-5 and ZSM-48 may be attributed to the unique two-dimensional channel structure for the ZSM-48. The ammonia desorption data also indicate that the influence of the channel system of ZSM-48 could play an important role in the molecular traffic control.