New fuels with high-energy-density are desirable for many combustion applications. Two types are reviewed in this paper namely, mixtures resulting from addition of certain metallic or nonmetallic elements to conventional hydrocarbon fuels, and newly synthesized hydrocarbon fuels with strained molecular conformations or more densely packed molecular structures. Despite the favorable effects of high-energy content, these materials often exhibit low reactivity and their ability to improve the performance of practical combustion systems relies strongly on their interaction with the dynamics of the surrounding fluid flow. The intensity of the combustion processes of these materials is dictated, in general, by the melting, evaporation, pyrolysis, mixing, and exothermic reactions processes. Unlike other conventional hydrocarbon fuels, all these processes time scales are often comparable with each other, causing difficulties to devise simpler theoretical models to predict the combustion characteristics. Both the advances made in recent years and the needs for future research and development in the field of energetic fuels are discussed.