The rational combination of transition metal oxides and carbon materials has been regarded as an efficient way of accessing the next-generation electrode materials for electrochemical capacitors. Here we demonstrate a facile synthesis of nanostructured MnO2 supported on carbon nanotubes (CNTs) via a direct redox route. By varying the reaction time, it can be convenient to control the growth density of MnO2 as well as the structural integrity of CNTs, which endow the novel hybrids with adjustable electrochemical performance. As a consequence, the resulting MnO2-CNT electrodes exhibit a maximum specific capacitance of 247.9Fg-1, with good rate capability and extraordinary cycling life stability (92.8% retention of initial capacitance after 5000 cycles), suggesting such materials have great potential in constructing high-performance energy-storage systems.