A two-dimensional polynuclear complex [Ni(mu(1.3)-SCN)(2)(mu-mpyo)](n) (where mpyo = 4-methylpyridine N-oxide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex there exist two kinds of bridging ligands, namely, mu(1.3)-SCN-bridging ligand and mu-mpyo bridging ligand. The two kinds of bridging ligands coordinate to Ni(II) ions in alternate fashion and it led to the formation of a two-dimensional sheet. The density functional calculations have been carried out on the binuclear model complexes to analyze the magnetic coupling mechanisms. The variable temperature (4-300 K) magnetic measurements were performed and the experimental data were fitted by using a binuclear Ni(II) magnetic coupling formula. The magnetic coupling constants from calculations are J = -61.81 cm(-1) for mu-mpyo bridging ligand and J = -13.31 cm(-1) for mu(1.3)-SCN-bridging ligand, and the experimental value is J = - 36.22 cm(-1.) In the area of magneto-structure theoretical calculation study this is the first paper that deals with the complexes with mixed bridging ligands. (c) 2005 Elsevier B.V. All rights reserved.