The molecular structure of trans,trans-bis[mu-bis(dimethylphosphino)methane-P:P']bis(dicyanonickel), [Ni-2(CN)(4)(C5H14P2)(2)], is Of the face-to-face type, It contains an eight-membered Ni2P4C2 ring with an elongated chair conformation and a transannular Ni ... Ni separation of 3.2085(6)Angstrom. The coordination geometry around the Ni atoms is square planar.