9-Ethoxy-8,8-di(triphenylphosphine)-9,10- tz H-8-rhoda-7-thia-nido-undecaborane( l O) dichloromethane solvate, C38Ha4B9OP2RhS.0.95(CH2C12), Mr = 891.7, triclinic, Pi, a = 10.271 (4), b = 11.401 (3), c = 19.426 (4)/~, a = 74.86 (2), 13 = 88.51 (3), y = 83.51 (3) °, V= 2182 (2)/~3, Z= 2, Dx = 1.357 g cm-3, graphite-monochromated Mo Ka radiation, a = 0.71073 A, /z = 6.5 cm-1, F(000) = 912, T= 294 K, R = 0.038 for 3984 observed reflections. The title compound contains an l 1-atom RhSB9 nido-structured cage with Rh and S atoms adjacent in the open RhSB3 face. An ethoxy group is bonded to the B atom adjacent to Rh in the open face with Rh--B9 2.119 (6) and B9--O 1.387 (9)A. The phosphine ligands are bonded to the Rh atom with one Rh--P bond [2.278 (2)A] trans to the S atom and the other [2.417 (1) A] located perpendicular to the open face of the cage.