<p>Food waste (FW) could be valorized through anaerobic digestion (AD) to produce bioenergy. However, it is necessary to develop an effective pretreatment method for FW to promote the methane production. To this end, this study investigated the effects of thermal-alkaline pretreatment (TAP) on the physicochemical characteristics of FW. An optimal condition (TAP, 80&#xa0;°C and 0.10 g NaOH/g TS for 1 h) was adopted to pretreat FW prior to semi-continuous anaerobic digestion for methane production. Results showed that the TAP improved the solubilization of particulate organic matters. Meanwhile, the concentration of total volatile fatty acids (TVFA) increased by 40.6% with considerable propionate, butyrate and valerate accumulation (18.35%). The overall methane yield of the TAP-AD process was 541 mL CH₄/g VS_removed on average, indicating an increase of more than 20% compared with that without TAP. Microbial analysis suggested that the enhanced methane production might be attributed to the syntrophic interaction with the availability of short-chain fatty acids, such as propionate, butyrate and valerate. It was estimated that net energy recovery in the TAP-AD was 18% higher than that without TAP. Overall, TAP proved to be a technically feasible and energy-effective pretreatment strategy for FW valorization through methane production in AD.</p> Graphical abstract