Modern concepts of lignin structure suggest that the ketol 1-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-2-propanone, VI, should be detectable in the hydrolysis products of lignin and wood. A reference sample of VI, previously unavailable, has now been prepared by catalytic hydrogenation of the diketone 1-(4-hydroxy-3-methoxyphenyl)-1,2-propanedione, II. Both fermentative and catalytic hydrogenation of II gave mixtures of, according to paper chromatography, mainly 2-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-1-propanone, V; the desired ketol, VI; small amounts of vanillic acid; and traces of guaiacyl acetone and an unknown phenolic compound. The ketol VI was isolated from the catalytic hydrogenation products by solvent fractionation and was identified by absorption spectra, derivatives, and comparison with the other two possible isomeric ketols. Dilute alkali converted VI to the isomeric ketol V. Both ethanolysis and acidolysis of VI gave the same monomeric products as lignin.