A new Ni (II) C pyrazine 2-carboxylic acid complex was synthesized. Single crystals were obtained for X-ray diffraction analysis and the crystal and molecular structures of the new complex were deciphered. The crystallographic parameters of complex compounds are as follows: Molecular formula is C10H10N4NiO6, Molecular weight is 340.91 k.v.; temperature during measurement is 100.0 (2) K; Absorption frequency is MoKα = 0.71073E, Syngonia – Monoclinic; space group is P2₁ /c, Crystal lattice parameters are: a = 5.2136Å, b = 11.10073Å, c = 10.15267Å; β = 100.1462⁰C, volume of the crystal lattice is V = 578.395ų, number of molecules in the crystal lattice is Z = 2, density is d = 1,956 g / cm³, absorption coefficient is 1,715 mm^-1, dimensions of the single crystal are 0,20x0.18x0,15 mm³; range of teta is 3.670–30.610⁰C; The boundaries of the hkl planes in the crystal section are h = -7+7 k = -15 +15.l = -14+14 the total number of collected reflexes is 8546, the number of independent reflexes is 1727, the boundary of the transitions is 0.761 and 0.707. Total  Rfactor = 0.0240. It has been found that the central Ni(II) atom is coordinated by one oxygen atom of the carboxyl group and a donor nitrogen atom of the pyrazine ring, forming five-membered stable bonds. Two water molecules are coordinated by the Ni(II) atom and complete the coordination number of the metal to six. The Ni–O bond distance is 2.0874 Å, the Ni-N bond distance is 2.0864 Å. The second oxygen atom is not coordinated by the Ni(II) atom and forms a strong hydrogen bond with coordinated water molecules

10.32737/0005-2531-2022-4-66-70