Hydrothermal Liquefaction (HTL) converts organic waste including food and plastics into energy-dense oil— a valuable fuel and chemical source—using water near or at supercritical conditions. Previous studies have used metals and more expensive, custom-designed catalysts to increase the oil yields of HTL. This study focuses on utilizing industrial waste metals as catalysts for HTL of plastics and biomass. By using waste metals, the cost of HTL catalysis would drop, and the waste would be repurposed instead of innovating new catalysts. The metals that positively affected oil yields were further analyzed to help explain their catalytic effect. These analyses investigated elemental composition of the oil and metal particles and size of the metal particles. These processes were also used to determine if the metals undergo changes in chemical composition after HTL. The project’s findings indicated that HTL can be improved through the addition of waste metals to increase its desirability as a waste-to-energy process and support future analyses of other potential catalysts to fully optimize the process.