A novel aminoxyl radical 4-(N-adamantanyloxyamino)-3,5-dichloropyridine (1), its hydroxylamine precursor (2) and copper(II) complex 3 with 1 were prepared and structurally characterized. The crystal structures of 1 and 3 showed the radical plane twists from pyridine ring. The density functional theory (DFT) calculation revealed that most of the spin (95.1%) locates on the radical group, while the pyridine nitrogen atom carries 0.4% spin. Temperature dependence of the magnetic susceptibilities (2-300 K) of 3 indicated intramolecular interaction between radical and copper(II) ion is ferromagnetic.