The synthesis of a new hexaaza macrocyclic ligand 3,7,11,19,23,27-hexaazatricyclo[27.3.1.(13,17)]tetratriaconta-1(32),13,15,17(34),29(33),30-hexaene, Me, by hydrogenation of the corresponding Schiff base is described. The crystal structure of its hexabromide salt, determined by means of X-ray analysis, is also reported. The compound with the empirical formula C28H52N6Br6 was obtained as a colorless plate crystallizing in the space group P1 as a triclinic crystal with the cell dimensions a = 7.966 Angstrom, b = 16.083 Angstrom, c = 7.8870 Angstrom, alpha = 93.45 degrees, beta = 97.26 degrees, and gamma = 102.28 degrees, with one molecule per unit cell. Protonation constants and metal ion stability constants of the mononuclear and dinuclear copper(II) macrocyclic complexes have been measured potentiometrically and are compared with those of analogous ligands. The different protonated forms of the basic ligand Mc recognize oxydiacetic acid and its anions forming nine strongly bound complexes. The formation constants for those complexes were determined with the use of potentiometric methods, and the nature of these complexes is discussed and compared with other analogous host-guest interactions.