The crystalline -MnO and -MnO nanorods have been successfully prepared via a facile hydrothermal method from -MnOOH nanorods precursor, respectively. The samples were characterized by means of X-ray diff raction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscope (FESEM) and Fourier transformed infrared spectra (FTIR). The morphology and structure of -MnOOH nanorods precursors have a great influence on the crystal structure of the obtained products. The -MnO nanorods are prepared from the 100°C -MnOOH precursor, while the -MnO nanorods are obtained from the 150°C -MnOOH precursor, respectively. Besides, the catalytic activity of the prepared -MnO and -MnO nanorods for the HO decomposition has been investigated comparatively, and the latter shows better catalytic activity.