The contribution focuses on the pore structure of mesoporous MFI and its catalytic properties in hexane isomerization. Base post treatment creates defected pore channels in MFI structure, thus enhances catalytic activity and unprecedentedly high dimethylbutane (DMB) yield far beyond shape selectivity restrictions. On the other hand, recrystallization post synthesis method forms a MFI/MCM-41 composite with MFI zeolite aggregates homogeneously supported inside MCM-41 channel and has the same global activity as MFI zeolite but having higher 23DMB product selectivity. The pore structures of both post treated MFI zeolite are elucidated from the changes in the product selectivity and sorption measurements.