An enthalpy of adsorption of ca. -10 kJ/mol was theoretically predicted for the interaction of molecular hydrogen with Mg-exchanged low silica chabazite (Si/Al = 5/1), which is significantly higher than the theoretical prediction for alkali-metal-exchanged chabazites (-3.0/-7.0 kJ/mol) and in acceptable agreement with a recent experimental finding of -17.5 kJ/mol obtained for a different zeolite, that is, (Mg,Na)-Y.