When the direct addition of thiophenol to phenylacetylene, p-bromophenylacetylene,p-nitrophenylacetylene, and propiolic acid was conducted at room temperature, the corresponding 1:1 adducts of traps-configuration were obtained, which were trans-β-phenyl-thiostyrene (Ⅰa),trans-β-phenylthio-p-bromostyrene (Ⅱa),and trans-β-phenylthioacrylic acid (Ⅳa) respectively. The yields of these adducts decreased in the following order:Ⅰa>Ⅱa>Ⅲa>Ⅳa. When the addition of thiophenol to the four acetylenes was carried out in solution at low temperature(-45~-35°),except p-nitrophenylacetylene which did not react under these conditions, all the other three compounds gave adducts only or mostly of cis-configuration (traps addition),which were cis-β-phenylthiostyrene (Ⅰb, 100%) cis-phenylthio-p-bromostyrene(Ⅱb, 75%) and cis-phenylthioacrylic acid (Ⅳb, 80%). All these compounds of cis-configuration were stable under the reaction conditions, being transformed to trans-configuration only on heating to or above 160°.