The electro-chemical discharge (ECD) phenomenon is a process producing electrical discharges in electrolytes by the application of voltage to an electrolytic cell. This process has the advantage of machining non-conducting material kept in the vicinity of the discharge. The study in this paper explores the influence of external circuit parameters on the discharge process. The experimental results of average voltage and current with NaOH and KOH electrolytes of 2, 5, 10 M concentrations with different circuit configurations are reported. The instantaneous voltage-current behaviour during discharge at 60 V of NaOH, KOH and HCl electrolytes are reported also for concentrations of 2 and 5 M. The best circuit configuration for the machining of non-conducting material is discussed. © 1995.