<p>Heavy oil recovery is challenging due to high viscosity. Thermal recovery technology can effectively improve the fluidity by injecting heat into reservoir. However, it often faces the issues related to high energy consumption and environmental impact during thermal fluid production. In this work, a supercritical water gasification (SCWG) system using waste cooking oil was proposed to generate hydrogen-enriched thermal fluid for enhancing heavy oil recovery. The feasibility was evaluated through thermodynamic analysis, life cycle assessment (LCA) and economic analysis. A hydrogen yield of 58.43&#xa0;mol/kg waste cooking oil was achieved at a temperature of 675&#xa0;°C, a pressure of 25&#xa0;MPa, and a feedstock concentration of 25&#xa0;wt%. The addition of hydrogen into heavy oil as hydrogen donor can increase the H/C atomic ratio of heavy oil, furtherly reduce the viscosity. The energy efficiency and exergy efficiency of the overall system were 69.20% and 67.34%, respectively. According to the analysis of LCA, the global warming potential of the system was 0.11&#xa0;kgCO₂-eq/MJ exergy, which was lower than other thermal fluid production systems using crude oil or biomass. Besides, the production cost of the hydrogen-enriched thermal fluid was estimated to be 206.74 $/t. Compared with other SCWG systems, this process offers higher efficiency, more environmentally performance and promising economic feasibility for the production of hydrogen-enriched thermal fluid by waste cooking oil to enhance heavy oil recovery.</p> Graphical Abstract <p></p>