<p>The recovery of kitchen waste (KW) is a crucial approach to alleviate energy supply shortages, and exploring efficient thermal conversion methods is of great importance in the energy sector. This study systematically compares the conversion performance of KW through torrefaction and hydrothermal carbonization (HTC) in the production of solid biofuels. The results show that with increasing treatment temperature, the product yields of both biochar and hydrochar as well as the H/C and O/C molar ratios decrease while the higher heating value (HHV) significantly increases. Biochar exhibits characteristics of surface fragmentation with fewer microspheres and disordered connections, whereas hydrochar forms more microspheres on the surface, has a rich carbon bonding structures, and significantly enhanced aromaticity. Under the same treatment temperature, HTC is more suitable for upgrading coal-like fuels as hydrochar has higher energy density and superior combustion characteristics. Energy balance analysis indicates that HTC yields higher net energy output at the same treatment temperature. Therefore, HTC shows greater potential for biofuel production compared to torrefaction. The findings of this study aim to provide a theoretical basis for optimizing reactor design and refining process conditions, contributing to further improvement of overall energy efficiency.</p>