Preliminary experiments have been completed which measure the leaching rate of soluble salts from spent oil shale as planned in the original research proposal. Presence of the shale matrix caused the diffusion rates to be approximately 8 fold slower than in aqueous solutions alone. Greskovich and coworkers have reported only 1.6 to 3 fold reduction in potassium chloride diffusion rates due to the presence of various sands and noninteracting muds. These preliminary observations suggest that leaching of soluble materials from retorted oil shale will proceed at considerably slower rates than would be predicted from leaching rate data observed in an inert matrix.