[en] During this period major progresses have been achieved for the studies of both univalent and multivalent hot atom reactions. Recoil tritium reactions with aromatic hydrocarbons have been initiated. The recoil ³¹Si reactions with 1,3-butadiene were studied. The reactions of ³¹SiF₂ and ³¹SiH₂ with trans-2-trans-4-hexadiene, its cis-trans-isomer and its cis-cis-isomer have also been studied. Four series of studies on the reactions of recoil ¹¹C atom reactions with butadiene have been performed. Another series of recoil ¹¹C studies involves the degradation of ¹¹C-labelled allene formed in the C₂H₄ system