Equilibrium methods were used to measure binding energies and entropies for the attachment of up to six H-2 ligands to ground-state Cu-2(+) ((2)Sigma(g), 3d(20) sigma(1)). Bond dissociation energies (BDEs) of the first five H-2 ligands added to ground-state Cu-2(+) are 12.4, 10.1, 4.9, 3.8, and 2.1 kcal/mol respectively, with the BDE of the sixth ligand approximated to be 1.7 kcal/mol. Entropy measurements indicated all six of the H-2 ligands were in the first solvation shell. Theoretical calculations at the DFT-B3LYP level were done on Cu-2(+) for the first four H-2 ligands. Vibrational frequencies and geometries were determined, and the origin of the bonding and its variation with Cu-2(+) coordination was examined. Comparisons are made to the Cu+(H-2)(n) and Zn+(H-2)(n) systems.