Two-dimensional cyanide-bridged (MNiII)-Ni-III bimetallic assembies, [Ni(1, 1-dmen)(2)](2)[M(CN)(6)]tfS.3.5H(2)O (M=Fe (1), Co (2); 1,1-dmen = 1,1-dimethylethylenediamine, tfs(-) = trifluoromethanesulfonate ion), have been prepared. Each compound forms a 2-D grid structure extended by the M-CN-Ni linkages. Compound 1 shows a ferromagnetic ordering below T-c of 8.9 K based on a ferromagnetic interaction between low-spin Fe-III and high-spin Ni-II. MCD spectra for I show a strong Faraday ellipticity at similar to470 nm associated with the LMCT band of the Fe-CN bond. Its intensity increases with lowering temperature due to ferromagnetic ordering over the lattice. Compound 2 is paramagnetic and shows no remarkable Faraday effect.