The conversion of renewable lignocellulosic biomass to alternative fuels seems a promising solution to the problem of depleting fossil fuels, global warming. In this work, hydrolysis of biomass-derived cellulose was investigated using -SO3H functionalized imidazole based ionic liquids (Es) with different aliphatic or aromatic linkers and anionic functionalities. These multifunctional ILs were synthesized in the laboratory and characterized using NMR, TGA, FTIR, and UV-Vis spectroscopy. ILs consisting of an aliphatic linker and triflate anion exhibited highest catalytic activity in cellulose hydrolysis with Total Reducing Sugar (TRS) yield of 93% at 100 degrees C and 90 min reaction time. Density Functional Theory (DFT) was used to calculate the acidity trends of the prepared catalysts and validated experimentally using FUR and UV Vis spectroscopy. ILs with aliphatic linker attached -SO3H group showed better catalytic performance as compared to aromatic or directly attached -SO3H group despite being less acidic. This was confirmed by TG analysis which showed the presence of water molecules in the aromatic and directly attached -SO3H (ILl & 3). Overall this report illustrates significant improvement over the prior art in terms of economic prospects with remarkable TRS production efficiency from renewable feedstock. (C) 2018 Elsevier Ltd. All rights reserved.