B3LYP and CCSD(T) calculations have been performed to determine binding energies (BE) and electronic structures of Li+ and Cu+ in their interaction with small ligands of the type HX (X = F, Cl, OH, SH, NH2, and PH2). BE of all ligands with Cu+ are higher than with Li+ with the exception of FH. For almost all ligands, the second ligand binds stronger than the first with Cu+ whereas the apposite trend was found for Li+ species. Water and ammonia bind with Cu+ by approximately the same bond length but the BE is 14 kcal/mol higher for NH3 because the latter is superior with respect to polarizability, induced dipole moments, charge transfer (CT), and sd(sigma) effects. Different from other ligands studied here, PH3 complexes are dominated by CT from the hydrogen atoms to the metal center through the phosphorus atom, leading to a different behavior of the ligand geometry changes when forming a complex. The MPn and CCSD(T) with TZP plus diffuse functions are necessary for accurate estimation of binding energies for Cu+ complex.