Lignin is one of main components in the most abundant lignocelluloses and is recognized as a unique renewable natural resource for the synthesis of aromatic chemicals. Its isolation and transformation have thereby attracted increasing attention in recent times. Here, an efficient method for the separation of lignin from sugarcane bagasse is reported using acidic ionic liquid catalysts. The structure and physicochemical properties and the molecular weight distribution of the isolated lignin were characterized by FT-IR, H-1 NMR and C-13 NMR, TG, elemental analysis, UV-vis, SEM and GPC. The results showed that acid functionalized ionic liquids are excellent catalysts for the delignification of sugarcane bagasse: 100% isolation of the desired product was achieved under optimized conditions. (C) 2012 Elsevier B.V. All rights reserved.