(dippe = 1,2-bis(di-iso-propylphosphino)ethane) (Mn1) as pre-catalysts for the hydrogenation of ketones, 22 nitriles and alkenes, 24 CO2, the boration and diboration of alkenes and alkynes, the dehydrogenative silylation of alkenes and the dimerization and cross coupling of terminal alkynes. Inspired by these results we wondered if Mn1 is also active in the semihydrogenation of alkynes. Herein, we report on the use of Mn1 as pre-catalysts for the E-selective semihydrogenation of internal alkynes and the conversion of terminal alkynes in MeOH as solvent in the presence of KBH4. We take advantage of the fact that the BH4 -anion undergoes fast alcoholysis to generate in situ hydrogen gas 29 which is required for the hydrogenation of alkynes without the need of high-pressure equipment such as autoclaves.