Electrospray ionization mass spectrometry was used for characterization of interaction between Ag+ and meso-octamethylcalix[4]pyrrole (1). Cation Ag+ forms with ligand 1 the complex 1·Ag+. By employing DFT calculations, four conformations of 1·Ag+ were derived. Ligand 1 can be considered as a macrocyclic receptor for Ag+.