Micro/nanostructures play a key role in tuning the radiative properties of materials and have been applied to high-temperature energy conversion systems for improved performance.Among the various radiative properties,spectral emittance is of integral importance for the design and analysis of materials that function as radiative absorbers or emitters.This paper presents an overview of the spectral emittance measurement techniques using both the direct and indirect methods.Besides,several micro/nanostructures are also introduced,and a special emphasis is placed on the emissometers developed for characterizing engineered micro/nanostructures in high-temperature applications (e.g.,solar energy conversion and thermophotovoltaic devices).In addition,both experimental facilities and measured results for different materials are summarized.Furthermore,future prospects in developing instrumentation and micro/nanostructured surfaces for practical applications are also outlined.This paper provides a comprehensive source of information for the application of micro/nanostructures in high-temperature energy conversion engineering.