Nanosized LiMn 2 O 4 spinel powder was synthesized by a spray-drying method. Compared to a solid-state reaction, this route not only reduces the high-temperature calcination time to a short time, but also effectively decreases the average particle size of LiMn 2 O 4 powders to the order of nanometers. XRD data indicate that nanosized LiMn 2 O 4 with short time calcinations has a high degree of crystallization with a well-defined spinel structure. In addition, the initial capacity at room temperature is markedly increased and the extent of capacity of degradation is reduced obviously at a high current density, showing a great potential for future applications.