In the title compound, 1,2-(SCH3)2-1,2-closo-C2B10H10 or C4H16B10S2, the methylsulfanyl groups are bonded to the C atoms of the 1,2-dicarba-closo-dodecaborane cage. The Ccage-Ccage distance is 1.8033 (18) A and the S-Ccage-Ccage-S torsion angle is 1.07 (13) degrees. The Ccage-Ccage distance is compared with those in other 1,2-dicarba-closo-dodecaborane derivatives.