The production of lignin from empty fruit bunch (EFB) has been carried out using liquefaction method with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid (IL), in presence of sulfuric acid (H2SO4) as a catalyst. Response surface methodology (RSM) based on a factorial Central Composite Design (CCD) was employed to identify the optimum condition for lignin yield. The result indicated that the second order model was adequate for all the independent variables on the response with R-2 = 0.8609. The optimum temperature, time, ionic liquid to EFB ratio, and catalyst concentration were 150.5 degrees C, 151 min, 3:1 wt/wt and 4.73 wt%, respectively for lignin yield = 26.6%. The presence of lignin liquefied product was confirmed by UV-Vis and FTIR analysis. It was also demonstrated lignin extraction from lignocellulosic using recycled IL gave sufficient performance. (C) 2012 Elsevier Ltd. All rights reserved.