Phenol and Cr(VI) are two dangerous organic and heavy metal compounds that are widely contained in the wastewater produced by industries, such as paint and textile industries. Conventional technology is still ineffective in treating the two types of waste, so it requires an appropriate waste degradation method. This study used plasma electrolysis technology with a methanol addition to decompose phenol and Cr(VI) wastewater concurrently, resulting in reactive species •OH and H•. Both reactive species are able to degrade organic and inorganic waste simultaneously. The research was conducted at voltage conditions of 650 V at the anode and 400 V at the cathode through the results of current and voltage characterization. After conducting the degradation test with variations of the plasma formation position, the concentration of methanol additives and the rate of air injection, the optimum conditions are anodic plasma, 0.1%v methanol concentration, and an air injection rate of 0.2 L/min. From these optimum conditions, the maximum percentage of phenol degradation was 96.36% and Cr(VI) 78% after 90 minutes of plasma electrolysis process. © 2024 AIP Publishing LLC.