We have obtained the direct evidence by high-resolution electron micro
scopy (HREM) that a pure MEL type zeolite has been successfully synthe
sized in an all-silica form using a novel organocationic templating ag
ent. It has been also confirmed from a synchrotron X-ray powder diffra
ction pattern obtained at room temperature that the crystal structure
of this all-silica zeolite is of the MEL-type by use of the Rietveld m
ethod.