Adsorption of ammonia, methylamine and 1-propylamine on alkali cation exchanged X zeolites was investigated using in situ IR spectroscopy and compared to sorption of water, ethanol and 1-propanol. Amines and alcohols formed similar primary adsorption complexes in the supercages of alkali cation exchanged zeolite X. Three elements contribute to the bonding, i.e., (i) the polar sorbate interacts with alkali metal cations via the lone electron pair of its electronegative atom, (ii) the protons of the functional groups of the sorbate form hydrogen bonds with the negatively charged oxygen atoms of the framework, and (iii) the hydrogen of the alkyl groups interact with the lattice oxygen. An-tines form only primary adsorption complexes and do not exhibit sorbate-sorbate interactions as observed for alcohols. (c) 2006 Elsevier B.V. All rights reserved.