Proton hopping between O-sites among different sites of the MCM-22 zeolite has been studied and compared for the first time by density functional theory. According to the results of calculation, it is found that both low and high hopping barriers (ranging from 4.96 to 28.82 kcal/mol) exist in the supercage as well as the sinusoidal channel systems, and there is no correlation between the proton transfer activation energy and proton affinity of the donor oxygen. The calculation also shows that other factors, the channel system and the geometric parameters of the equilibrium state, affect the hopping barriers of different sites. (C) 2004 Elsevier B.V. All rights reserved.