A novel ternary complex of [NiL1L2·2H2O]·NO3·H2O (L1 = 2-hydroxyl-1,10-phe- nanthroline (HOphen), L2 = 2-hydroxynicotinic acid (H2nicO)) was synthesized, and its crystal structure was determined by X-ray diffraction and further characterized by infrared and elementary analysis. The title complex (C18H18NiN4O10, Mr = 509.07) belongs to the triclinic system, space group P1 with a = 7.2490(7), b = 11.0164(10), c = 13.3864(13) ?, α = 91.6040(10), β = 98.8620(10), γ = 107.1140(10)o, V = 1006.43(17) ?3, Z = 2, Dc = 1.680 g/cm3, μ = 1.032 mm?1, F(000) = 524, the final R = 0.0461 and wR = 0.1238. In the complex, the Ni(II) ion is six-coordinated to assume a distorted octahedral geometry, and a 3D supramolecular network comes into being via weak intermolecular interactions of X–O…H (X = N, O).