A family of planar disc-like hexa-, octa- and decametallic Ni-II complexes exhibit dominant ferromagnetic exchange. The deca- and octametallic clusters [Ni-10(II)(tmp)(2)(N-3)(8)(acac)(6)(MeOH)(6)] (1, H(3)tmp = 1,1,1-tris(hydroxymethyl)propane; acac = acetylacetonate) and [Ni-8(II)(thme)(2)(O2CPh)(4)(CI)(6)(MeCN)(6)(H2O)(2)] (2, H(3)thme = 1,1,1-tris(hydroxymethyl)ethane) represent rare examples of Ni-II-based single-molecule magnets, and [Ni-10(II)] (1) possesses the largest barrier to magnetisation reversal of any Ni-II single-molecule magnet to date.