Upgrading corncob residues (CCR) to a high quality energy resource is an effective utilization of an underutilized industrial lignocellulose waste. A hydrothermal carbonization technique was therefore employed to generate a high heating value (HHV) hydrochar. Results showed that its HHV increased 47% after treatment at 230 degrees C for 1.5 h. Decreases in H/C and O/C verified that reductions in C and O reactions were occurring following hydrothermal carbonization. The chemical and thermal properties of the final hydrochar as analyzed by FT-IR, TG/DTG, and XRD analyses indicated that dehydration and decarboxylation were the predominant pathways for the C and O reductions. The present hydrothermal carbonization process is offered as a promising approach to upgrade CCR to a high heating value hydrochar under mild conditions