Table summarises the study of the influence of various types of substituents at the ethynyl moiety on its conversion and selectivity towards the desired product. Phenylacetylenes decorated with a methyl substituent located at the aryl group were converted with excellent anti-Markovnikov regioselectivity (>99%) to linear (E)-alkenyl pinacol boronic esters. However the conversions after 1h were rather moderate (59-75%). As expected, the steric hindrance influences the reaction rate and 4-ethynyltoluene reacted faster than 3-and 2-ethynyltoluene (75% vs 61% vs 59% conversion, entries 2-4). When using 4-ethynyltoluene, extending reaction time to 24 h allowed for a nearly complete conversion of the alkyne. Phenylacetylene bearing electron-withdrawing bromo substituent underwent hydroboration by HBpin without any loss of regioselectivity, but with a moderate conversion of only 35% after 1h (entry 6). The phenylacetylene derivatives with either a phenyl (entry 10) or a methoxy (entry 7) group at para position did also react much slower, giving only 40% and 68% of conversion, respectively. In both these cases, an extension of the reaction time 24 h increased the conversions to 87% and 99 %, respectively. On the other hand, weakly electron-donating p-tert-butyl group did not affect the reactivity of the phenylacetylene derivative (entry 5). Aliphatic alkynes were also successfully converted into adequate pinacol boronic esters. Similarly, an excellent anti-Markovnikov regioselectivity was observed, however, the alkyl substitution had a small negative effect on the catalyst activity, as the conversions were slightly lower. We then turned our attention to ethynylsilanes as another group of substrates whose hydroboration could possibly lead to potent building blocks -(E)-1-silyl-2-borylethenes. We carried out hydroboration of ethynyldimethyl(phenyl)silane (entry 12) and ethynyltriisopropylsilane (entry 13) with pinacolborane in the presence of NaHBEt3 (1M in toluene) as a catalyst. As it turned out, hydroboration of ethynylsilanes was not as effective as that of previous alkynes. The reaction with ethynyldimethyl(phenyl)silane resulted in moderate conversion of the substrate giving the corresponding product with only 80% of regioselectivity towards the linear ester. A higher regioselectivity of >99% was observed with the use of ethynyltriisopropylsilane, however, the conversion was sill moderate. Noteworthy, trimethylsilylacetylene did not react at all. Representative examples of hydroboration products were isolated and analysed.