A chain-like carbon nanostructure, which we call as carbon nano-chains (CNCs), was synthesized through chemical vapor deposition (CVD). The influence of growth conditions (such as growth temperature, time and gas ratio) during CVD process on the carbon structures and the growth mechanism of the CNCs were investigated. To explore the potential application as electrode materials of supercapacitors, the electrochemical performances of the CNCs and the CNCs activated with KOH have been tested. The results indicated that the original CNCs exhibit relatively high specific surface area, high purity and regular framework, and favor growth at a moderate temperature and mild gas ratio. After activation, the CNCs have much improved specific surface area and porous structure. The electrochemical performance investigations showed that the activated CNCs have a power density of 159.6 kW kg⁻¹ and an energy density of 15.5 W h kg⁻¹, as well as excellent cycle stability, which is very superior to the original CNCs. This simple and low-cost preparation process and the superb electrochemical performance suggest great potential applications of activated CNCs in supercapacitors.