Ferri- and gallo-silicate analogues of NCL-1, a high silica large pore zeolite, have been synthesized and characterized through spectroscopic methods (XRD, IR, ESR and solid state MAS NMR), ion exchange capacity, adsorption (n-hexane, 1,3,5-trimethylbenzene and water), BET surface area and catalytic activity and selectivity in Bronsted acid catalyzed conversion of 1,3,5-trimethylbenzene measurements. These data were compared with those exhibited by Al-NCL-1 analogue. During 1,3,5-trimethylbenzene (mesitylene) isomerization into 1,2,4-trimethylbenzene (pseudocumene), the conversion decreased in the order : Al- > Ga- > Fe-NCL-1 (at the same reaction temperature, WHSV and time on stream). However, the selectivity for pseudocumene and isomerization selectivity (vis-a-vis disproportionation) followed the reverse order at comparable conversion level.