The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert neutron kinetic energy into heat, breed tritium for the fuel cycle and accommodate a heat transfer system. Various blanket concepts have been considered including those incorporating liquid metals, molten salts, water and He. The objective of this review is to outline some of the critical compatibility issues associated with structural materials being considered for designs operating at >500°C. Examples are given for vanadium alloys, magnetohydrodynamic coatings, oxide dispersion strengthened ferritic alloys and silicon carbide composites.