Research on metallic corrosion in coalgasification atmospheres has primarily involved testing in high-Btu pilot plants or laboratory simulations thereof, although the near-term economic feasibility of low-Btu processes in combined-cycle electric-power production appears promising. Consequently, information on the operating parameters (vessel pressures, gas compositions, and maximum temperatures) for eleven low-Btu gasifiers was analyzed to characterize the gaseous environments in terms of the oxygen, sulfur, and carbon potentials in these systems. In general, the product gas from low-Btu gasifiers exhibits lower oxygen potentials than that from high-Btu gasifiers. Sulfur is a more important corrodant than carbon in these environments. A comparison of the environments in various high- and low-Btu processes shows that even the conventional high-chromium alloys, such as Type 310 stainless steel and Incoloy 800, will develop a sulfide mode of attack in nearly all low-Btu atmospheres, regardless of the sulfur content of the coal feedstock. The results also show that there exists a threshold in oxygen partial pressure above which a continuous protective oxide scale is developed on the alloys. At 1144 and 923 K, this threshold oxygen partial pressure is, respectively, ∼103 and ∼105 times the oxygen partial pressure for the Cr oxide/Cr sulfide equilibrium. The analysis of the process environments and the experimental evidence clearly shows that novel design approaches and alternate materials are needed for effective utilization of coal via low-Btu gasification schemes.