Theoctanuclear Eu clusterEu8(DMF)13(μ4-O)(μ3-OH)12(Se3)(Se4)2(Se5)2has been synthesized by the reaction of EuCl3 (dissolved intetrahydrofuran) with a polyselenide solution in dimethylformamide(DMF). Its structure (shown without the DMF molecules) comprises atriangulated dodecahedral Eu8 core centered by aμ4-O and face capped by 12 hydroxo groups. Fivebidentate polyselenide chains and 13 DMF molecules complete thecoordination spheres of the Euatoms.