Conjugate acid oxidation of benzyl esters with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and trifluoroacetic acid (TFA) was applied to the binding site analysis of ester linkages between lignin and glucuronoxylan in Fagus crenata wood. Based on the conjugate acid DDQ-oxidation of a watersoluble lignin-carbohydrate complex (LCC-WE) from the beech wood, the frequency of the ester bonds between the lignin and glucuronic acid residue of glucuronoxylan was determined to be 1.6 per molecule of LCC-WE.