The Mediated Electrochemical Oxidation (MEO) process was studied for destroying low-level combustible mixed wastes at Rocky Flats (RFP). Tests were performed with nonradioactive surrogate materials: Trimsol for the contaminated oils, and reagent-grade cellulose for the cellulosic wastes. Extensive testing was carried out on Trimsol in both small laboratory-scale apparatus and on a large-scale ... [Show full abstract] system incorporating an industrial-size electrochemical cell. Preliminary tests were also carried out in the small-scale system with cellulose. The following operating and system parameters were studied: use of a silver-nitric acid versus a cobalt-sulfuric acid system, effect of electrolyte temperature, effect of acid concentration, effect of current density, and use of ultrasonic agitation. Destruction and coulombic efficiencies were calculated using data obtained from continuous carbon dioxide monitors and total organic carbon (TOC) analysis of electrolyte samples. For Trimsol, the best performance was achieved with the silver-nitrate system at high acid concentrations, temperatures, and current densities. Destruction efficiencies of 98% or greater and coulombic efficiencies close to 50% were obtained in both small- and large-scale systems. For the cellulose, high destruction efficiencies and reasonable coulombic efficiencies were obtained for both silver-nitrate and cobalt-sulfate systems.