Two diadochy cyanide-bridged bimetallic complexes [Pr(DMSO)2(H2O)3Co(CN)6]·H2O 1 and [Nd(DMSO)2(H2O)3Co(CN)6]·H2O 2 have been synthesized, and their crystal structures were determined by single-crystal X-ray diffraction methods. Crystal data for 1: monoclinic, space group P21/c, a = 7.692(2), b = 30.791(10), c = 9.131(3) (A), β =100.645(5)o, V = 2125.4(11) (A)3, Z = 4, the final R = 0.0422 and Wr = 0.0904 for 3484 observed reflections with I > 2σ(I); and those for 2: monoclinic, space group P21/c, a = 7.692(3), b = 30.902(11), c = 9.152(3) (A), β = 100.665(5)o, V = 2137.8(13) (A)3, Z = 4, the final R = 0.0515 and wR = 0.0906 for 3268 observed reflections with I > 2σ(I). The LN atoms are linked to the Co atoms by cyanide bridging, forming a two-dimensional gridding structure. The LN3+ ions are both eight-coordinated by three cyano nitrogen and five oxygen atoms of two DMSO and three water molecules. The X-ray single-crystal structure analysis shows that the unbridged cyanide ligands between the closest layers interact with the coordinated water molecules through hydrogen bonds to connect the two layers. Therefore, the molecular structure is a 3D hydrogen-bonded network derived from LNCo chains.