Hydrothermal pretreatment is a thermochemical process utilizing hot water or steam, often under pressure, to modify the structure and composition of a material, typically biomass or waste streams. This methodological approach investigates the effects of elevated temperature and pressure on material breakdown, component separation (such as solubilizing hemicellulose or lignin), and the enhancement of subsequent processing steps like enzymatic hydrolysis or fermentation, aiming to improve resource utilization and conversion efficiency.