This work aims to study the effect of copper supplementation (as CuCl₂), at different concentrations (10, 30, and 50 mg/L Cu²⁺) to enhance the conversion of organics present in a mixture of food waste and domestic wastewater (0.183, v/v) to biogas. The UASB reactor was operated under mesophilic conditions (350.1^。C) at hydraulic retention time of 10 days in the intermittent feed mode (48 h feed/48 h feedless). Regardless of the Cu²⁺ concentration supplemented, a higher cumulative biogas yield (260-329 mL CH₄/g COD_removed) was obtained compared to the control without supplementation (175 mL CH₄/g COD_removed). The microelement supplementation reduced the amount of short chain fatty acids accumulated in the reactor by 35%, stimulating the methane production.