A series of soluble metal phenoxides prepared from two phenols was investigated as high-temperature (to 371 C) anti-oxidants in polyphenyl ether (5P4E). Compounds from Group 1A (alkalis) and 2A (alkaline earths) were effective, but not in the same order as their inorganic oxide, hydroxide and carbonate counterparts studied earlier. High-temperature antioxidant activity of the phenoxides was not adversely affected by water-saturated air; the phenoxides were, however, subject to hydrolysis at 40 C by persistent exposure to liquid water. The phenoxides did not adversely affect the pyrolytic stability of the ether in the absence of air, although they were themselves slightly degraded.Presented at the 29th Annual Meeting in Cleveland, Ohio, April 28–May 2, 1974