Enzymatic hydrolysis residues (EHR) are the solid wastes from enzymatic hydrolysis and/or fermentation of the cellulosic bioethanol industry. These byproducts have not been effectively used. Thermogravimetric analysis with infrared spectroscopy (TG-IR) and pyrolysis-gas chromatography/ mass spectrometry (Py-GC/MS) were used to quantify the pyrolytic bioenergy potential of EHR with alkaline hydrogen peroxide (AHP) and bisulfite (BSF) pretreatment through assessing their pyrolysis behaviors, kinetics, and byproducts. The TG-IR analysis showed that the EHR pyrolysis temperature range was 180 °C to 620 °C and consisted of three consecutive stages: dehydration, rapid pyrolysis, and carbonization. The main volatile products evolved from the EHR pyrolysis were CO, CO2, H2O, and CH4. Fast pyrolysis results from Py-GC/MS indicated that the main pyrolytic byproducts of EHR were phenols (30.68%), furans (14.27%), and acids (8.52%) for AHP-EHR; and phenols (26.75%), furans (15.54%), and acids (10.33%) for BSF-EHR. The results provide insights for expanding the potential of bioenergy and increasing the value-added byproducts based on the biomass part of EHR.