The efficiency of chemical transformations of lignin obtained from Picea excelsa wood under the action of galactose, galacturonic acid and xylose (which can be obtained by enzymatic hydrolysis of hemicelluloses and pectin containing in plant material) was evaluated. The results were compared with use of traditional reducing agent which was borohydride sodium. Using the method of differential UV-spectroscopy was confirmed the increase of a number of phenolic hydroxyl units by Xyl, Gal and GA. The increase of lignin reactivity was controlled to sulfuric acid and to peroxide hydrogen. Similarly to NaBH4, a nucleophilic addition mechanism for the reaction of the reducing saccharides with lignin was revealed. Reduction by NaBH4, Xyl, GA and Gal increased the lignin reactivity to acid solubilisation and to peroxide oxidation.