We have extensively studied the magnetic features of a heterometallic molecular trimer, Cr 2 Cu. We have characterized molecular Cr 2 Cu by low-temperature ac susceptibility and specific-heat measurements and this allowed us to determine the microscopic parameters of the spin Hamiltonian. Then, we used x-ray magnetic circular dichroism to selectively probe local symmetries, electronic configuration, orbital, and spin magnetic moments of the magnetic ions. We found that at low temperatures only the ground state S= 3/2 is occupied and the spin of Cu is found opposite to that of Cr in agreement with spin-Hamiltonian calculations.