Technical Abstract: Lignocellulosic biomass has the great potential to serve as the low cost and abundant feedstock for bioconversion into fermentable sugars, which can be further utilized for biofuel production. However, high lignin content, crystalline cellulose structure and the presence of ester linkages between lignin and hemicellulose in the plant cell wall limit the enzymatic accessibility for efficient saccharification. Various physical and chemical pretreatment methods are currently employed to break down the biomass recalcitrant structures, and increase their susceptibility to enzymes. Amoung these techniques, dilute acid pretreatment has been shown as a leading pretreatment process. However, dilute acid hydrolysis can lead to degradation products that are often inhibitory and significantly lower the overall sugar yields. Glucose and xylose degradation products that result from the pretreatment methods include hydroxymethylfurfural (HMF) and furfural, which produce levulinic and formic acids, respecively, which inhibit the subsequent fermentation of sugars to ethanol. Recently, ionic liquids have demonstrated great promises as efficient solvents for biomass dissolution with easy recovery of cellulose upon anti-solvent addition. However, to date, no comprehensive side-by-side comparative analysis has been conducted in order to evaluate the dilute acid and ionic liquid biomass pretreatement processes. In this study, we are comparing ionic liquid and dilute acid pretreatments acting on switchgrass with numerous analytical techniques to gain a better understanding of both techniques and their saccharification efficiency into fermentable sugars for downstream biofuel production.