Thermolysis of phenyl benzoate on heating under reflux for ca. 10 days in a nitrogen atmosphere gives phenol, o- and p-hydroxy biphenyl, biphenyl, and carbon monoxide. Phenyl phenylacetate under the same conditions gives toluene, bibenzyl, stilbene, phenol, o- and p-benzylphenol, 9-phenylxanthene, water, and carbon monoxide. Thermolysis of benzyl benzoate is accompanied by decarboxylation and the formation of toluene, diphenylmethane, bibenzyl, stilbene, and biphenyl. Thermolysis of benzyl phenylacetate proceeds smoothly, affording carbon dioxide, toluene, bibenzyl, and stilbene. It was concluded that thermolyses of esters proceeds through a free radical mechanism involving homolytic fission of either the O—CO or O–alkyl bond with subsequent decomposition of the radicals so formed.