Abstract The naphthalene ruthenacarboranes 3-(η-C10H8)-3,1,2-closo-RuC2B9H11 (1), 4-(η-C10H8)-4,1,6-closo-RuC2B10H12 (2) and 4-(η-C10H8)-4,1,10-closo-RuC2B10H12 (4) have been synthesised by the general method of reaction of a carborane dianion with [RuCl2(COD)]x in the presence of excess naphthalene under THF reflux. Compounds 4-(η-C10H8)-4,1,8-closo-RuC2B10H12 (3) and 4-(η-C10H8)-4,1,12-closo-RuC2B10H12 (5) were prepared from 2 and 4, respectively, by thermolysis in refluxing toluene. Compounds 1–5 were characterised spectroscopically and crystallographically. For the supraicosahedral ruthenacarboranes 2–5 the main structural point of interest was the conformation of the naphthalene ligand with respect to the ruthenacarborane cage, in comparison with conformations of the analogous ferracarboranes 4-(η-C10H8)-4,1,x-closo-FeC2B10H12 previously studied computationally. Good agreement is found between experimental and computational conformations for compounds 2, 3 and 4. Crystallographic disorder in 5 renders comparison between theoretical and experimental conformations difficult in this case.