The dependence of global reactivity descriptors on electronic structure method as well as basis set is investigated for typical reactions in zeolite catalysis. This research is especially focused on hard−hard interactions between small probe molecules (such as chloromethane, methanol, ethylene, and propene) and different zeolite clusters containing both oxygen and amine functionalities. The performance of novel hybrid metafunctionals (such as BMK and MPWB1K) on crucial reactivity predictors is assessed through comparison with both Hartree−Fock and B3-LYP results. For the complex bifunctional zeolite systems, we find accurate results using any of the DFT functionals, in conjunction with a basis set of at least double-ζ quality further augmented with both polarization and diffuse functions. Reactivity sequences, based on global softness differences as well as activation hardness values, are generally found to be independent of the level of theory whenever a DFT functional is used.