Abstract In order to examine the possibility of the direct introduction of the sulf hydryl radical into ethylene or propylene and that of the telomerization by means of a silent discharge, the mixture of ethylene or propylene and hydrogen sulfide was discharged in an ozonizer. (1) With ethylene and hydrogen sulfide, the main products were ethyl mercaptan, n-butyl mercaptan, and ethylene dithioglycol. Besides these compounds, the reaction products were confirmed to be diethyl sulfide, s-butyl, n-hexyl, n-propyl, and isopropyl mercaptans, and gaseous products. (2) With propylene and hydrogen sulfide, on the other hand, n-propyl mercaptan, di-n-propyl sulfide, isopropyl mercaptan, and 1,2-propyIene dithioglycol were obtained as the main products. Besides these compounds, there were diisopropyl sulfide, ethyl and n-butyl mercaptans, 4-methyl-1-pentene, 2,3-dimethylbutane, 1,5-hexadiene, 2-methylpentane, 1-hexene, n-hexane, and gaseous products. The maximum yield of the liquid products was obtained when ethylene or propylene and hydrogen sulfide were mixed in approximately the ratio of 1:1. Judging from the relative concentration of each compound in the reaction products, it may be said that vinyl, ethyl, and sulfhydryl radicals in the reaction system of ethylene and hydrogen sulfide, and 2-methylvinyl, isopropenyl, propyl, allyl, isopropyl, and sulfhydryl radicals in the reaction system of propylene and hydrogen sulfide, are the main intermediates.