The purpose of this paper is to review corrosion processes and experience related to coal-fired gas turbines. For over 40 years there have been major programmes of research directed towards burning coal in a gas turbine either directly or as a coal-derived fuel. This history is briefly reviewed, demonstrating the importance which corrosion of the hot section has had in limiting the achievements and defining the systems. The probable corrosion mechanisms are identified, and because of their synergistic interaction with corrosion, erosion and deposition are also considered. The discussion identifies pressurized fluidized bed combustion (PFBC) as the direct combustion technique most likely to be able to avoid serious corrosion problems in the immediate future. Recent results from PFBC pilot plant investigations related to turbine materials are compared, and thereby future directions for overcoming corrosion problems are proposed. MST/449