Reaction between the cluster salts [(eta(5)-CP')(3)M3S4][pts] (M = Mo, W; Cp' = methylcyclopentadienyl; pts = p-toluenesulfonate) and [Co-2(CO)(8)] yielded the electroneutral clusters [(eta(5)-CP')(3)M3S4Co-(CO)]. The molecular structure of [(eta(5)-CP')(3)W3S4Co(CO)] was determined by single-crystal X-ray diffraction methods. The unprecedented 60 electron W3S4Co cluster completes a homologous series of heterobimetallic clusters, [(eta(5)-Cp')(3)M3S4Co(CO)] (M = Cr, Mo, W), containing a cubane-like core motif.