With the aid of a secondary reagent [CuII(tren)](ClO4)2, a novel chiral one-dimensional coordination polymer, [NiII(tren)]3[MoIV(CN)8](ClO4)2·5H2O (1) (tren = tris(2-aminoethyl)amine), was inadvertently but reproducibly synthesized, which crystallizes in a chiral space group P212121 and shows a complex triple-stranded helical structure.