Abstract: The plasma degradation of crystal violet by glow discharge electrolysis is presented.The factors for the degradation and/or decoloration processes were studied.The decoloration efficiency of crystal violet could be increased considerably by increasing electrolyte concentration and voltage applied.After considering the service life of the Pt electrode used,an electrolyte concentration of 2 g/L Na₂SO₄ and an applied voltage of 600 V were chosen as the optimum experimental conditions.Increasing the initial pH of the solution could accelerate the decoloration of crystal violet.Addition of H₂O₂ can increase the rate of decoloration,too.Furthermore,the presence of 0.4 mmol/L Fe²⁺ can improve the decoloration rate of crystal violet from 13.64% to 91.36% within 5 minutes.The addition of a radical scavenger n-butanol decreases the decoloration efficiency of crystal violet,which shows that hydroxyl radicals play an important role in the degradation process.Based on ultraviolet (UV) absorption spectra obtained during the degradation process,more than 93% crystal violet was decolorized,and 74% crystal violet was degraded after oxidation for 40 minutes.The possible degradation pathway for crystal violet is proposed.The results show that the combination of glow discharge plasma,H₂O₂ and/or Fe²⁺ can accelerate the degradation of crystal violet considerably.