Five-coordinate bis(carbodithioato)tris(ethylenediamine)-nickel(II) complexes are obtained by reaction of piperidine-, morpholine-4-, piperazine-4-,N-methylpiperazine-4-, and thiomorpholine-4-carbodithioato nickel derivatives with ethylenediamine. The square planar starting complexes react with three moles of ethylenediamine to give five-coordinate products with the dithio ligands acting in a monodentate fashion only. The new complexes were characterized by their far i.r., near i.r. and electronic spectra, as well as by magnetochemical investigations and conductivity measurements. The most attainable geometry is square pyramidal, probably slightly distorted; tentative assignments for the electronic spectra are proposed. The room temperature magnetic moments show that all the complexes are of high-spin type, the values lying in the ranges usually observed for other high-spin penta-coordinated nickel(II) derivatives. The metal-sulphur and metal-nitrogen stretching vibrations are also assigned.