The physicochemical characteristics of nanosized energetic materials (aluminum, ammonium nitrate, RDX) are studied and the burning rate of energetic condensed systems containing nanosized components is determined. The morphology, chemical purity, and thermal properties of nanosized powders produced by vacuum and plasma recondensation were examined. The materials obtained are identical to the precursors and are characterized by an increased reactivity compared to their microsized counterparts. At a pressure of 100 atm, a monopropellant prepared from nanosized RDX particles is found to have twice as high the burning velocity as a microsized RDX propellant. For nanoaluminum-ammonium perchlorate compositions, the burning velocity is demonstrated to be an order of magnitude higher than that for similar compositions with microsized aluminum. An important feature of nanoaluminum-based formulations is a decrease in the degree of agglomeration of metal fuel products and, hence, in two-phase losses in solid-propellant rocket engines.