A method has been developed for the determination of free phenolic groups in softwood lignin. It is based on the colour reaction occurring between 1-nitroso 2-naphthol and eugenol. The colour reaction of l-nitroso-2—naphthol with a variety of substances containing one or two guaiacyl nuclei (representing probable structural prmcipales of lignin) has been investigated. The number of free phenolic hydroxyls per methoxyl group in milled soft wood lignin was determined. Satisfactory agreement was obtained with results reported in the earlier literatüre.