A highly electroactive polypyrrole with hollow “horns” in micro/nanometers (h-PPy) is galvanostatically prepared by a template-free approach in p-toluenesulfonate alkaline solution. Its electrochemical capacitance properties are characterized to verify its promising applicability for supercapacitors. Besides its high specific surface area, h-PPy shows unexpectedly good ordering of molecular chain and great conjugation length, contributing to high ionic and electronic conductivity. These advantages lead to a remarkable specific capacitance of 400Fg−1 and ultrafast charging/discharging capability with a specific capacitance of 274Fg−1 at the charging/discharging time of even 0.4s. Moreover, the micro/nanostructured hollow “horns”, which can tolerate the mechanical stress in charging/discharging process, significantly improve the cycle life of h-PPy so that the capacitance retains 90% after 100,000 continuous cycles. All of its distinguishing quality enable h-PPy to be an excellent active material of supercapacitors.