AbstractXylose-extracted corncob residue (X-ER), a byproduct from the xylose production industry, is a potential cellulose-rich energy resource. However, attempts to achieve large-scale production of cellulosic ethanol using X-ER have been unsatisfactory due to a lack of understanding of the substrate. This study presents the first characterization of the X-ER to evaluate its potential utilization in the sequential production of cellulosic ethanol. The current dilute acid treatment procedures used for the corncobs by the xylose-production industry were insufficient for efficient deconstruction of cellulose structure to release available sugars for subsequent cellulosic ethanol conversion. After a secondary dilute acid hydrolysis of the X-ER, an additional 30% hemicellulose was recovered. In addition, a more efficient enzymatic hydrolysis of X-ER was observed resulting in a significantly higher yield of glucose conversion compared with an untreated X-ER control. These results suggest X-ER can be utilized for cellulosic ethanol production. However, improved corncob pretreatment procedures are needed for economical cellulosic ethanol conversion.