Catalytic intermolecular hydrophosphination of alkynes with Ph2PH has been achieved by using a ytterbium–imine complex,[Yb (η2-Ph2CNPh)(hmpa) 6]. Thus, both terminal and internal alkynes were converted in high yields to the corresponding alkenylphosphines or phosphine oxides after oxidative workup. The present method was also applicable to various carbon carbon multiple bonds such as conjugated diynes and dienes, allenes ...