To gain an understanding of the various factors which are likely to contribute to the overall extraction of metal cations by alkyl p-tert-butylcalix(4)arene esters, different approaches are considered. Thus, ligand-solvent interactions are detected from transfer enthalpies of calixarene esters in the appropriate solvents obtained calorimetrically. Conductance measurements are used to determine stability constants of metal cations and these ligands and ion-pair formations for the single and complexed electrolytes with the anion in the non-aqueous medium. Thermodynamic data (free energies, enthalpies and entropies) of complexation involving calixarene esters are for the first time derived from titration microcalorimetry and some representative data are reported. The extraction of metal cations from aqueous solutions by water insoluble calixarene esters is discussed. © 1994, Walter de Gruyter. All rights reserved.