Treatment of guaiacylglycerol- and guaiacylpropanediol-β-(2-methoxyphenyl) ethers at 160 C in 50 % alcohol containing magnesium bisulfite was found to cleave the β-aryl ether linkages in these compounds to form isoeugenol and/or eugenol in up to 60 % yield as well as comparable yields of guaiacol. The linkage in a nonphenolic model was not cleaved to a discernible extent. Both an alcohol and bisulfite were essential for this reductive cleavage which proceeded efficiently in ethanol and isopropanol but not efficiently in methanol,t-butanol or dioxane. Magnesium was a better base than sodium for the reaction.