The thermal docompoeition of optically activo mothylothylacotyl peroxide in carbon t)trachloride gave s-Imtyl chloriMe,2-butanone,methylethylacetic acid ( probably in the form of tlio acid chloride),s-butyl methylethylacetate and hoxachloroethane.Decomposition in bromotricliloromethane gave chloroform,s-butyl bromide,methylethylacetic acid,s-butyl methylethylacetate and hexachloroothane.Carton dioxide and other gaseous products were not collected.The optical inactivity of s-butyl chloride and s-butyl bromide,together with tho results of Pau Ⅰ (preceding paper),supports the general view that a free radical is incapablo of maintaining its stexoo-configuration.Control runs showed that tho s-butyl halides were optically etablo under the experimental coeditions.