A non-thermal arc plasma reactor with two metal tube electrodes has been tested for the production of hydrogen from ammonia decomposition.Systematic study was carried out to investigate the influence of different electrode materials,such as stainless steel (SS),Al and Cu,on ammonia conversion.Results show that SS electrodes were better than Al and Cu in terms of ammonia conversion.Interestingly,we observed an approximately 240 minute’s induction period for SS electrode reactor,in which ammonia decomposition conversions increased from 64％ to 82% (Fig.1).To gain an insight into the induction period,three kinds of pretreatments on the SS electrodes were performed with H2,N2 and NH3/He mixture,respectively.Among them,the pretreatment of NH3/He mixture (80 ml/min,NH3/He=1:1,25 W) eliminated the induction period,while no obvious influence was observed with H2 and N2 pretreatment at the same condition.