In the ionic title compound, [Ni(NO3)(C10H9N3)(2)]NO3, the central Ni-II atom exhibits cis-NiN4O2 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 center dot center dot center dot O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO3)(2) and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO3)(2)/dpya/maleic acid/NaOH system.