Mixed-ligand Ni(II) complexes involving thiodiglycolate(2−) anion (tdga) and nitrogen-donor ligands in the coordination sphere have been prepared. The complexes of composition [Ni(bpy)(tdga)(H 2O)] · 4H 2O ( 1), [(en)Ni(μ-tdga) 2Ni(en)] · 4H 2O ( 2), [Ni(phen)(tdga)(H 2O)] ( 3), [Ni(1,8-dan)(tdga)(H 2O)] ( 4), [Ni(nphen)(tdga)(H 2O)] · H 2O ( 5), [Ni(ampy)(tdga)(H 2O)] ( 6), where bpy=2,2 ′-bipyridine, en=ethylenediamine, phen=1,10-phenanthroline, 1,8-dan=1,8-diaminonaphthalene, nphen=5-nitro-1,10-phenanthroline and ampy=2-(aminomethyl)-pyridine, have been characterized by elemental analysis, IR and UV–Vis spectroscopies, and magnetic susceptibility measurements. Room temperature effective magnetic moments for 1– 6 are ranging from 3.06 to 3.28 μ eff/ μ B. and thus indicating that nickel atoms are six-coordinated in a deformed octahedral arrangement in all the prepared complexes. This conclusion has been confirmed by single-crystal X-ray analysis of [Ni(bpy)(tdga)(H 2O)] · 4H 2O ( 1). A binuclear structure of complex [(en)Ni(μ-tdga) 2Ni(en)] · 4H 2O ( 2) has been anticipated in connection with study of its magnetic properties over the 1.8–300 K temperature range ( J=−4.35 cm −1, D=5.53 cm −1, zJ=−0.94 cm −1 for g=2.00) and unambiguously proved by a single-crystal X-ray analysis.