Monte Carlo simulations were performed for Cu 2 + in 4.8%, 10%, 18.6% and 30% aqueous ammonia solution at temperature of 293.16 K, using ab initio pair potential and three-body potentials for Cu 2 + -H 2 O-H 2 O, Cu 2 + -H 2 O-NH 3 and Cu 2 + -NH 3 -NH 3 . The fully solvated Cu 2 + in 4.8%, 10%, 18.6% and 30% aqueous ammonia solution can be characterised as [Cu(H 2 O) 6 ][(H 2 O) 2 2 ] 2 + , [Cu(H 2 O) 4 (NH 3 ) 2 ][(H 2 O) 2 0 ] 2 + , [Cu(H 2 O) 3 (NH 3 ) 3 ][(H 2 O) 1 1 . 6 (NH 3 ) 1 0 , 2 ] 2 + (J. Chem. Phys. 112 (2000) 4212) and [Cu(H 2 O) 2 (NH 3 ) 4 ][(H 2 O) 5 . 9 (NH 3 ) 1 7 . 5 ] 2 + , respectively. The structure of the solvated ion is discussed in terms of radial distribution functions, coordination number and angular distribution.