Smooth single-crystal α-Mn2O3 nanowires have been fabricated using a one-step solid-state reaction method. X-ray diffraction patterns show that the nanowires have pure phase of α-Mn2O3. Transmission electron microscopy was employed to investigate the size and morphology of the products. The α-Mn2O3 nanowires exhibit mean diameter of 50nm and length of 10μm. Selected-area electron diffraction pattern demonstrates the single-crystal structure of the α-Mn2O3 nanowires, which are in good agreement with the X-ray diffraction results. The processes of the reactions and the phase transitions were also studied by using a simultaneous thermal gravimetric/differential thermal analyzer. It is found that the concentration of the precursor MnCO3 is a crucial factor in the formation of the nanowires. This work provides the probability of the industrialization of fabricating smooth single-crystal α-Mn2O3 nanowires.