Abstract: Adsorption characteristics of ammonia on H-mordenite (HM) at various temperatures have been studied by IR spectra and .differential thermal techniques. The relative amounts of reversible and irreversible adsorption of ammonia and their changes with temperature are measured. Moreover, IR spectra of ammonia on HM and its catalytic activity for toluene disproportionation reaction are determined under conditions approximating those that are actually carried out for this. Experimental results show that the adsorption of ammonia on L-site is reversible, but that on B-site is irreversible. It has been proved that B-site is the catalytic active center for toluene disproportionation reaction.It seems that under our experimental conditions L-sites do not play a direct role in disproportionation reaction