Synthesis and application of copper oxide (CuO) nanoparticles-decorated activated carbon for use as a cathode material in microbial fuel cells (MFCs) is introduced. The CuO-decorated activated carbon was prepared by dissolving copper nitrate in ethanol, followed by the addition of activated carbon to the copper nitrate/ethanol solution. The resulting slurry was dried and thermally treated at 300°C for 3 hours. The copper nitrate was used at a concentration of 7 wt.% relative to the activated carbon. X-ray diffraction analysis confirmed the presence of CuO nanoparticles on the activated carbon. The modified activated carbon was then used to fabricate the cathode. This involved mixing the CuO-decorated activated carbon with polyvinylidene fluoride polymer and dimethyl formamide to form a paste, which was subsequently cast onto carbon cloth. The coated carbon cloth was then thermally treated at 280°C. The anode was prepared from graphitized corncob, treated under an inert atmosphere at 900°C. An air cathode, single-chamber MFC was assembled and operated using sewage wastewater. The power and current densities were monitored over a period of two weeks, with maximum current and power densities of 2.12 A/m² and 0.466 W/m² achieved after 7 and 9 days, respectively.