Summary Laboratory flow tests have been carried out to study the stability of various nickel-coated sands under aqueous steam temperature and pH conditions that may exist in thermal recovery operations. Other gravel-pack materials tested include Ottawa sand, sintered bauxite, cement clinker, zirconium oxide, and nickel pellets. A comparison was made between the performances of these materials after exposure to identical thermal and hydrolytic conditions. Test results indicate that nickel-coated sands are highly resistant to dissolution at temperatures as high as 300°C [570°F] and to solution pH's from 4.75 to 11. Weight losses measured after a 72-hour period were less than 1%. In contrast, weight losses from sintered bauxite, zirconium oxide, and Ottawa sand dissolution tests were 30 to 70 times higher under the same conditions. Cement clinker losses were in the intermediate range under alkaline conditions. API standard crushing and acid-solubility tests for proppants also were performed on nickel-coated sands. These results were favorable in that they exceeded the recommended standards. This study of nickel-coated sand stability and mechanical strength has demonstrated its high potential for application as either a gravel-pack material or proppant in thermal recovery operations.