In this study, rice straw and sugar cane bagasse were pretreated using a novel imidazole:poly(ethylene glycol) (IPEG) solvent at temperatures between 120 and 200 °C for 1 h. The pretreatment using IPEG with molecular weight of PEG of 200 g/mol (IPEG200) resulted in 83% and 92% of xylan from rice straw and bagasse, respectively, being converted to furfural. The solubility of xylan was highest in IPEG200, which had higher hydrogen bonding acidity, hydrogen bonding basicity, and polarizability. The yield of glucose from pretreated residues via enzymatic hydrolysis was highest for rice straw treated with IPEG200 (27%) compared to the untreated sample (9%). Pretreatment of sugar cane bagasse using IPEG200 resulted in higher yield of furan derivatives (600 g/kg) compared to that from rice straw. The pyrolysates from the enzymatic hydrolysis residues contained a significantly lower amount of carboxylic acid and furan derivatives due to the removal of hemicellulose during the pretreatment process. © 2019 American Chemical Society.