In the ionic title compound, [Ni(NO(3))(C(10)H(9)N(3))(2)]NO(3), the central Ni(II) atom exhibits cis-NiN(4)O(2) octahedral coordination with three chelating ligands, viz. one nitrate anion and two di-2-pyridylamine (dpya) molecules. A second nitrate group acts as a counter-ion. The complex cations and the nitrate anions are also linked by N-H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO(3))(2) and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO(3))(2)/dpya/maleic acid/NaOH system.