Hydroboration of terminal and internal alkynes has been also successful using transition metal-free, boron-containing catalysts (e.g. B(C6F5)3, borenium cations, HB(C6F5)2, tris[3,5bis(trifluoromethyl)phenyl]borane, tris(2,4,6-trifluorophenyl)borane, H3B•THF) , , , , , however, to the best of our knowledge, there is only a single report on the use of commercially available sodium triethylborohydride in this process. NaHBEt3 has been demonstrated by Thomas and coworkers to catalyse hydroboration of phenylacetylene with pinacolborane to give (E)-styryl boronic ester in 45% yield. We have already reported that NaHBEt3 can be used as a selective catalyst for dehydrogenative silylation of alkynes with hydrosilanes and Markovnikov-selective hydrosilylation of alkenes. , Given the preliminary report from the Thomas group and the mechanistic similarity of hydrosilylation and hydroboration reactions, we decided to study in more detail the reactivity of terminal alkynes and pinacolborane in the presence of alkali metal triethylborohydrides in order to examine the impact of these commonly used reductants on the course of the hydroboration process.