Abstract: The electroactive material of α-Cobalt hydroxide was prepared using cobalt chloride and ammonia as raw materials by a simple chemical precipitation method. The structure of Co(OH)2 was characterized using X-ray diffraction (XRD) and the component was analyzed by FT-IR. Thermal stability of Co(OH)2 was measured by thermal analysis, including thermogravimetry (TG) and differential thermogravimetry (DTG). The electrochemical performance was investigated by cyclic voltammetry and constant current charge/discharge technology. The results show that the prepared material was pure α-Co(OH)2 which had bad thermal stability, but excellent electrochemical performances. Its specific capacitance as single electrode was 543.8 F·g-1. And after 1 000 cycle charge and discharge, the specific capacitance was 72% of the initial capacity.