[en] Recoil sulfur atoms from the nuclear transformation of ³⁵Cl(n,p) ³⁵S were allowed to react with gaseous ethane in the presence or absence of various additives. Hydrogen sulfide was one of the main products, with the yield remarkably affected by the addition of nitrogen monoxide. The yield was increased at low concentration levels of nitrogen monoxide, but decreased at high concentration levels. The primary yield of hydrogen sulfide was estimated to be ca 7.8% of which ca. 3.6% was scavengeable by oxygen. The scavengeable yield is considered to be a product of the reaction of thermalized sulfur atoms. The photochemically produced sulfur atoms are known to yield no hydrogen sulfide in reaction with ethane. The discrepancy between the recoil reaction and the photochemical reaction was investigated using various additives. (orig.)