Recent studies suggest that the chromium content in sludge wastes stored at the U.S. Department of Energy＇s Hanford Site will determine the amount of high-level borosilicate glass produced in immobilizing those wastes for disposal. Removing chromium from the sludge solids would reduce the mass of high-level borosilicate glass, which would likely result in a significant cost savings. We have been investigating oxidative leaching methods for removing chromium from Hanford wastes for a number of years. In these methods, chromium(III), which is insoluble under alkaline conditions, is converted to the soluble chromate ion. We have removed chromium on a laboratory scale from several different Hanford tank sludges. The most effective leaching agents investigated to date are permanganate and ozone, which readily oxidize chromium(III) to chromium(VI) under alkaline conditions.