AbstractCommon secondary aromatic amine and alkylated phenolic antioxidants lose much of their activity in polyethylene containing carbon black. In contrast their thioether derivatives provide more protection against oxidation than the sum of the separate contributions of carbon black and the sulfur compounds. Organic disulfides and some thio‐ethers without amino or phenolic hydrogen also safeguard polyethylene from oxidation but only in the presence of carbon black. Likewise thiols are excellent protectants in combination with carbon black but not in clear polymer. Aliphatic thiols, disulfides, and their polymeric derivatives and related selenium compounds exhibit similar activit