The continued improvement in efficiency of high-temperature structures depends on improved materials and on designs that utilize these materials more effectively. This paper discusses the possibilities available to achieve these improvements. While the results are applicable to any high-temperature structure, the discussion focuses on gas turbine engines. This is because some of the most demanding requirements correspond to this application and the author is more familiar with this area. Possible materials can be separated into distinct classes: evolutionary and revolutionary materials. The former represent incrementally improved materials, mostly metals. The latter represent intermetallic compounds, and metal, polymer and ceramic composites. An attempt is made to estimate the extent of improvements that can be realized from each class of material. In addition, the barriers to realization of the gains are outlined. Where possible, next steps in overcoming these are described. Finally, non-technical issues such as material cost and availability are addressed and the growing importance of these factors is discussed.