A novel dimerized Ni-dithiolene complex, (n-Bu4N)(2)[Ni(dmit)(i-mm)](2) (1), was synthesized and characterized by X-ray structure analysis. In this complex two [Ni(dmit)(i-mnt)] units were mutually connected by two long axial Ni-S bonds. The single crystals of TTF, BEDT-TTF and EDT-TTF salts with [Ni(dmit)(1-mnt)](2)(2-) were prepared by electrocrystallization and characterized by X-ray analyses. The Ni-S bonds of each dimer were also retained in these salts. Each salt exhibited semiconducting behavior.