High-temperature, high-power capacitors are integral components being developed for high-temperature electronics to be used in aerospace, automotive, and other applications. Presently, a wide range of materials and capacitor technologies are being actively developed to address the needs of high temperature applications. Literature and experimental survey of existing materials and technologies focusing on commercially viable technologies has been made. Key parameters for characterizing and assessing capacitors have been compiled. Of the key competing capacitor technologies, including electrolytic, ceramic, polymer thin-film, and supercapacitors, none were found to be clearly superior to the others, thus requiring trade-offs between available choices. The review of these capacitors will be presented with respect to specific energy density, temperature capability, cost, ripple current capability, and failure tolerance. In addition to presenting a survey of existing capacitors, we have experimentally characterized RC constants as a function of temperature for a wide variety of materials including dielectric polymers, simple oxides, ferroelectrics, and glasses. While in general there is a trade-off between R and C parameters for different materials, outstanding RC's were observed in lanthanum doped BaZrO3 ceramics and ferroelectric inorganics with high-temperature phase transitions. © 2008 SAE International.