Supercapacitors are promising energy storage devices due to their evident advantages such as high power density, friendly environment, high safety and convenient operation over a wide range of temperature, long cycle and shelf life. supercapacitors are able to charge and discharge much faster by absorbing and desorbing charges on the surface of electrodes. The above advantages of supercapacitors have made them promising candidates to serve as the next generation energy storage technology. Materials with desirable properties is the key for realizing high-performance supercapacitors In this book, manganese oxide nanostructures were prepared, characterized and evaluated as supercapacitor electrodes. Mn3O4 octahedrons and Porous Mn3O4 nanostructures with a high surface area exhibited the superior electrochemical performance.