Abstract: The adsorption heats on h-mordenite (HM) have been investigated by flow-DTA adsorptive calorimetric technique. Plots of differential absorption heats. (Q_d) of ammonia, pyridine, benzene, toluene and p-xylene at 200 ℃ against varying adsorption amounts (A) were given respectively. There appears a turning point on the plot of Q_d of ammonia vs. A, which shows that there are two kinds of acid sites on HM, one is strong with the adsorption heat of ammonia in the range of 120-155 kJ mol~(-1), and the other weak in the range of 70—85 kJ mol~(-1). For the purpose of getting the information about the adsorption of aromatic compounds on different adsorption regions containing different kinds of acid sites. the adsorption heat of benzene and toluene on HM partly and totaly poisoned by ammonia were respectively measured. The results dempstrate that the non-physical adsorption of aromatic compounds only occurs on the regions containing acid sites, nevertheless, the adsorption strength of aromatic compounds is different from that of ammonia on each region.