Although many transition-metal catalysts are ineffective for the addition and carbonylative addition of organic disulfides to internal alkynes, dicobalt octacarbonyl ([Co-2(Co)(8)]) was found to exhibit excellent catalytic activity for the carbonylative bisthiolation of internal alkynes. In the presence of carbon monoxide, a wide variety of organic disulfides successfully underwent addition to internal alkynes to afford the corresponding beta-sulfanyl-alpha,beta-unsaturated thioesters in good yields.