The new thioantimonate [Ni(tren)2]2[Ni(tren)(en)]2(Sb4S8)2·0.25H2O (tren = tris(2-aminoethyl)amine; en = ethylenediamine) was obtained under solvothermal conditions. The compound crystallizes in the non-centrosymmetric space group P1 with a = 9.424(2), b = 13.010(3), c = 18.883(4) Å, α = 102.46(3), β = 96.11(3), γ = 90.92(3), V = 2246.1(8) Å3, Z = 1. Two of the unique Ni2+ cations are octahedrally surrounded by two tridentate acting tren ligands (type 1) and the other two Ni2+ cations are in an octahedral environment of one tetradentate tren molecule and one bidentate en ligand (type 2). The antimony atoms are in a trigonal pyramidal environment of three sulfur atoms. The SbS3 pyramids are corner-linked to form two individual [Sb4S8]4– chains running parallel to . Along  the two different types of Ni2+-centered complex cations and the thioantimonate chains alternate. The interchain separations between [Sb4S8]4– chains depend on the space requirements of the two different types of complex cations. Extended N–H···S hydrogen bonding interactions between the complex cations and the anionic chains generates a three-dimensional network.