The results from several leaching studies using retorted oil shale from the Rifle mine in Colorado and both demineralized, de-ionized water and Rock Springs groundwater are reported. The shale used in the groundwater leaching was retorted at temperatures ranging from 430 C to 780/sup 0/C in the absence of air for 30 hr. The 780/sup 0/C retorted shale was then leached with the groundwater for 450 hours while the 430/sup 0/C retorted shale was leached for 400 hr. The leachate from the 780/sup 0/C experiment showed a greater increase of calcium, lithium, and potassium in the groundwater than did that from the shale retorted at 430/sup 0/C. Sodium, iron, and carbonate concentrations in the groundwater decreased during the leaching of both 780 C and 430/sup 0/C retorted oil shales, with the larger decrease occurring with the shale retorted at the higher temperature. While the magnesium concentration in the groundwater decreased during the leaching of the high temperature retorted shale, it showed a slight increase during the leaching of the 430/sup 0/C retorted shale. The pH of the leachate also showed an increase with increasing retorting temperature. For the de-ionized water leaching experiments, the oil shale was retorted over the same temperature range as in the other experiments whether in the presence or absence of air. In the experiments with the shale retorted without air, the leachate showed an increase in lithium, sodium, potassium and pH with increasing retort temperatures, while magnesium showed the opposite behavior. Calcium in the leachate showed a maximum concentration at 630/sup 0/C. The behavior of all the ion concentrations in the leachate from the shale retorted in the presence of air was similar to that retorted without air, except that greater amounts of materials, besides lithium and magnesium from the high temperature retorted shale, were leached from the shale retorted in the presence of air. 75 figures, 167 tables.