A cooperative study with the Locomotive Development Committee of the Bituminous Coal Research Association and the Crucible Steel Company of America was conducted with S-588 heat-resisting alloy at 1350 F. In order to observe the possible stress-corrosion effects of coal ash on this material, stress-rupture tests of specimens in contact with raw coal ash from representative Illinois coal and specimens coated with separated Illinois coal ash were compared with “blank” specimens. In addition to S-588, several other metals of interest to the builders of gas turbines for locomotive service were also tested in unstressed condition at 1000, 1350, and 1500 F. in contact with representative Ohio coal ash. In these tests, specimens cut from flat sheet or bar stock were grouped in a casserole with only about one-half of the specimens underneath the ash. The tests demonstrate that these coal ashes or coatings from coal ash are inert to these alloys at these temperatures.