The past several years have seen a dramatic increase in research interest regarding ordered and disordered mesoporous molecular sieves. UL-ZSM5s belong to the class of disordered mesoporous materials where zeolites are intergrown in mesoporous structures. They are considered to have a great potential for adsorption separation and catalysis. The primary objective of this study is to investigate the main diffusion path of these novel materials, using the zero length column (ZLC) technique with an appropriate theoretical analysis. Two UL-ZSM5 samples and their precursors were investigated, employing o-xylene as a probe molecule. In addition, ZSM-5 and ZSM-12 crystals with n-heptane/toluene as probe molecules were used as reference systems. The results revealed that the structure of UL-ZSM5 and its precursor behaved approximately as a three-dimensional (isotropic) diffusion system, while ZSM-5 and ZSM-12 crystals behaved as three- (isotropic) and one-dimensional (anisotrpic) diffusion systems, respectively. The results also showed that the diffusion path will not change with the variation of temperature or nature of sorbate molecules. From a practical point of view, this simple and relatively inexpensive method can be conveniently used as an additional tool for the characterization of porous materials.