By means of ESR (electron spin resonance) spectroscopic investigations it is shown, that in dithiol/diene-mixtures, in the absence of daylight and oxygen, radicals are formed spontaneously. Using the spin trapping technique and nitrosodurene (ND) as the trapping agent the existence of sulfur and carbon radicals could be proved unambiguously. Oxygen has no significant influence on the reaction. Spin trapping experiments have shown, that the aliphatic dithiols investigated do not form any traceable quantity of RS. and .OOH radicals in the presence of air. Radicals are detected only after addition of an ene-compound.