RhH(PPh(3))(4) and 1,1'-bis(diphenylphosphino)ferrocene catalyze the regio- and stereoselective additions of diaryl disulfides and diaryldiselenides to 1-alkynes giving (Z)-1-arylseleno-2-arylthio-1-alkenes. The catalyst promotes the addition reaction of dibutyl disulfide and dibutyl diselenide to 1-octyne with a similar selectivity giving (Z)-1-butylseleno-2-butylthio-1-octene but with a lower catalytic