A new series of hybrid organometallic-inorganic layered magnets with formula [Z III Cp* 2 ] [M II Ru III (ox) 3 ] (Z III ؍ Co and Fe; M II ؍ Mn, Fe, Co, Cu, and Zn; ox ؍ oxalate: Cp* ؍ pentamethylcyclopentadienyl) has been prepared. All of these compounds are isostructural to the previously reported [Z III Cp* 2 ] [M II M III (ox) 3 ] (M III ؍ Cr, Fe) series and crystallize in the monoclinic space group C2/m, as found by powder X-ray di4raction analysis. They are novel examples of magnetic materials formed by bimetallic oxalate-based extended layers separated by layers of organometallic cations. The magnetic properties of all these compounds have been investigated (ac and dc magnetic susceptibilities and 5eld dependence of the isothermal magnetization at 2 K). In particular, it has been found that Fe II and Co II derivatives behave as magnets with ordering temperatures of 12.8 and 2.8 K, respectively, while no long-range magnetic ordering has been detected down to 2 K in the Mn II and Cu II derivatives. The magnetic ordering in the Fe II derivatives has been con5rmed through MoK ssbauer spectroscopy. This technique has also made it possible to observe the spin polarization of the paramagnetic [FeCp* 2 ] ؉ units caused by the internal magnetic 5eld created by the bimetallic layers in the ordered state.