The complexation reactions between different amines and the macrocyclic ligand 18-crown-6 have been studied in methanol. Calorimetric titrations have been performed in order to obtain the stability constants and the reaction enthalpies and entropies for these reactions. The stability constants of all amines studied are within the same order of magnitude. However, alkyl and aryl substituents strongly influence the values of the reaction enthalpies and entropies. In contrast, for all secondary and tertiary amines examined nearly identical values for the reaction enthalpies and entropies are observed. As a result, the number of hydrogen bonds formed between the crown ether and these amines is not the most important factor.