The existence of a sulfonium and sulfonium-type radical intermediate in some free-radical reactions of phenyl sulfide has been studied. It has been found that the t-butoxy radical with phenyl sulfide gives phenyl sulfoxide and the t-butyl radical; these could form via a sulfonium-type radical intermediate. The cumyloxy radical and benzophenone triplet were apparently not reactive enough to give the intermediate, and alkyl radicals gave indefinite products. © 1964, American Chemical Society. All rights reserved.