Degradation of nickel- and cobalt-base superalloys in corrosive, particleladen gas streams is being investigated by injecting salt and abrasive particles into a high-velocity combustor. The test conditions being used are intended to simulate the mechanism of materials degradation expected in coal-fired gas turbines where components will be subjected to hot corrosion from impurities in the coal and high-velocity impingement of fly ash particles. Oxidation-erosion experiments (with abrasive particles but no salt), considered a prerequisite for understanding the more complex case of erosion-hot corrosion, defined regimes of particle size and flux where the following situations were observed: (1) material loss predominantly by mechanical erosion, (2) material loss by an oxidation-erosion interaction, and (3) deposition of the solid particles on the leading edge of the cylindrical test specimens. A preliminary erosionhot corrosion experiment showed a marked interaction between sulfate-induced hot corrosion and particulate erosion; the rate of metal consumption was much greater than that attributable to the sum of erosion and hot corrosion processes acting alone.