A novel dielectric-barrier-discharge (DBD) loop reactor was designed for the efficient degradation of cyanide anion (CN-) in water. The circulation of cyanide water as a falling film through plasma gas discharge zone enhanced gas-liquid mass and energy transfer and induced formation of H2O2 which was associated with the efficient destruction of CN-. It was observed that among different discharge gases, the CN- degradation rate decreased in the order of Ar > air > H-2/air mixture. Depending on discharge voltage, the treatment time for complete removal of 100 ppm CN- in this DBD loop reactor is in the range 120-300 min. The dose of Cu2+ catalyst in combination with in situ production of H2O2 enhanced the destruction of CN- apparently in this DBD loop reactor. The treatment time for complete degradation of 100 ppm CN- decreased from 180 min with Ar DBD discharge alone to 40 min with 40 mg/L dose of Cu2+ ion in water, making it an efficient means to degrade cyanide water.