Stereo- and regioselectivity of the addition of benzenetellurolate ion (PhTeNa), formed in situ from (PhTe)2, and NaBH4 in ethanol, to acetylenic bonds have been studied. Its addition to monosubstituted acetylenes such as phenylacetylene, 1-octyne, and propargylic alcohols proceeded completely in a trans fashion to afford a regioisomeric mixture of the corresponding vinylic tellurides, the attack of PhTe moiety occurring mainly at the terminal carbon (terminal/internal=ca.80∼90/10∼20) except the case of phenylacetylene where the ion attacked completely the terminal carbon. No reaction was observed with 4-octyne, while diphenylacetylene afforded a low yield of the addition product. In the case of propiolic acid esters the addition of PhTe moiety occurred completely regioselectively at acetylenic β-carbon, while a small amount of cis-addition product was always formed (trans' cis= ca 95/5). Benzenetellurol(PhTeH), formed in situ by methanolysis of (phenyltelluro)trimethyl. silane, showed a very low reactivity for this addition.