tetrakis(triphenylphosphine)platinum(0), allenes undergo carbonylative thiolation with carbonmonoxide and thiols to provide the corresponding α,β- and β,γ-unsaturated thioesters in good yields. In contrast, the use of rhodium(I) catalysts such as RhH(CO)(PPh3)3 in place of Pt(PPh3)4 leads to copolymerization of allenes and carbonmonoxide without incorporation of thio groups.