Lignins isolated from cotton stalks, jute stick and dhaincha by acidolytic dioxane were characterized using alkaline nitrobenzene oxidation, elemental analysis, methoxyl analysis and molecular weight analysis and UV, IR H-1 NMR spectroscopy. The C, formulas for cotton stalks, jute stick and dhaincha (Sesbania aculeata) lignin were C9H9.36O4.50(OCH3)(1.23), C9H9.02O4.57(OCH3)(1.35) and C9H8.88O4.65(OCH3)(1.50), respectively. All three lignins were of the guaiacyl-syringyl type. Cotton stalks lignin contained more p-hydroxy phenyl unit than dhaincha and jute stick lignins as observed by alkaline nitrobenzene oxidation products. The beta-O-4 units in these nonwood lignins had predominately erythro stereochemistry type. (c) 2006 Elsevier Ltd. All rights reserved.