Waste-to-Energy (WTE) and biomass-fired power generation systems are gaining in popularity worldwide as a means of cleanly disposing of waste and generating needed power in the same operation. Due to the variety of components in the feedstock conditions vary greatly in the combustion sections of these systems. Municipal solid waste (MSW) often contains significant quantities of plastics which introduce halogens and halides into the environment when burned. Their presence greatly increases the corrosion rate of iron-base materials thus necessitating the use of higher nickel alloys. However many of the feed constituents can be rich in sulfur and phosphorus which are very detrimental to the performance of nickel-base alloys. Thus the makeup of the feed to be burned largely dictates the optimum materials for use in the boiler. The performance of several iron- and nickel-base materials are evaluated with respect to the environment and conclusions are drawn as to the optimum products for various components of different power generation systems.