A potential negative electrode material (mesoporous nano-Co3O4) is synthesized via a simple thermal decomposition of precursor Co(OH)2 hexagonal nanosheets in the air. The structure and morphology of the samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that the nano-Co3O4 is present in mesoporous hexagonal nanoparticles. The average size of holes is about 5–15nm. The electrochemical performances of mesoporous nano-Co3O4 as the active starting negative electrode material for alkaline secondary battery are investigated by galvanostatic charge–discharge and cyclic voltammetry (CV) technique. The results demonstrate that the prepared mesoporous nano-Co3O4 electrode displays excellent electrochemical performance. The discharge capacity of the mesoporous nano-Co3O4 electrode can reach 436.5mAhg−1 and retain about 351.5mAhg−1 after 100 cycles at discharge current of 100mAg−1. A properly electrochemical reaction mechanism of mesoporous nano-Co3O4 electrode is also constructed in detail.