Nucleophilic attack of thiols on phenylacetylene (1) in liquidammonia at room temperature gave the corresponding Z-isomer of styryl sulfides in high yield stereoselectively. Reaction of 1 with Na2S also proceeded selectively to give Z,Z-distyryl sulfide (12). On the other hand, reaction with NaSH gave 12 besides E,Z-isomer as a minor product.