Nanospheric hydroxo-bridged clusters of [M-20(OH)(12)(maleate)(12)(Me2NH)(12)](BF4)(3)(OH)center dot nH(2)O (M = Co (1), Ni (2)) with Oh symmetry were afforded under hydrothermal condition with Co(BF4)(2)center dot 6H(2)O/Ni(BF4)(7)center dot 6H(2)O and fumaric acid in a DMF/EtOH mixed solvent. They are characterized by elemental analysis, IR, and X-ray diffraction. X-ray single crystal diffraction analyses show that these two complexes are isostructural containing an ideally cubic M-8 core in that each two M atoms are doubly bridged at the edges by one OH- and one maleate, while these OH- and maleate groups are coordinated further by exterior identical 12 M atoms which construct a perfect M-12 icosahedron to encapsulate the cubic core. To our knowledge, such large clusters with O-h symmetry are seldom. The variable-temperature magnetic susceptibility studies reveal that these two isostructures exhibit antiferromagnetic interactions.