Pretreatment is one of the most important steps in the production of bioethanol from renewable feedstocks like lignocellulosic biomass, however, existing pretreatment approaches have some,limitadons. In this context, two different acid-functionalized magnetic nanoparticles (MNPs) i.e. alkylsulfonic acid (Fe3O4-MNPs@Si@AS) and butylcarboxylic acid (Fe3O4-MNPs@Si@BCOOH) were synthesized and evaluated for their efficacy at different concentration in the pretreatment of sugarcane bagasse. It was observed that both of these acid-functionalized MNPs showed concentration-dependent promising catalytic activity as compared to conventional acid pretreatment. Both Fe3O4-MNPs@Si@AS and Fe(3)O(4)MNPs@Si@BCOOH at 500 mg/g of bagasse showed the maximum amount of sugar (xylose) liberated i.e. 18.83 g/L and 18.67 g/L, respectively which are comparatively higher than the normal acid pretreatment (15.40 g/L) and untreated sample (0.28 g/L). Further, both the acid-functionalized MNPs used were recovered by applying magnetic field and reused for next two subsequent cycles of pretreatment. Therefore, such nanotechnology-based approaches can be used as a rapid and eco-friendly alternative method for the pretreatment of a variety of lignocellulosic materials. Moreover, the reuse of the same MNPs for more than one cycle of pretreatment can also help to reduce the cost involved in the process. (C) 2019 Elsevier Ltd. All rights reserved.