Single-crystal α-MnO2 nanotubes are synthesized by a facile hydrothermal method without the assistance of a template, a surfactant and heat-treatment. The single-crystal α-MnO2 nanotube electrode possesses a high specific capacitance with a good power capability. The excellent pseudo-capacitive properties are attributed to a nanotubular microstructure and a large tunnel cavity in the α-MnO2 crystal structure. Single-crystal α-MnO2 nanotubes with good electrochemical performance can be a promising candidate as supercapacitor materials.