Abstract: Co（OH）₂/MWCNTs composite was prepared by room-temperature solid-state reaction method.The product′s crystal shape，composition，and morphology were characterized by XRD，FT-IR，and SEM.Results indicated that β-Co（OH）₂ parti- cles prepared by solid-state reaction were uniformly coated on multi-walled carbon nanotubes（MWCNTs）.Electrochemical tests showed that both the specific capacitance and cycle performance of the obtained composite were effectively improved.The specific capacitance became constant gradually and a high number of 385 F/g could be obtained for the Co（OH）₂/MWCNTs composite with the MWCNTs mass fraction of 10% after 200 charge-discharge cycles.The capacitance increased by about 8% after 1 000 cycles，that was，415 F/g could be achieved，showing its excellent cyclic stability.

Key words: room-temperature solid-state reaction, Co（OH）₂/MWCNTs composite, electrochemical capacitance