Electrical Discharge Machining (EDM) is a non-conventional machining process in which the material removal occurs by utilizing thermoelectric energy. EDM’s inherent properties render it a feasible method in machining hard-to-cut materials, like tool steels. The current study presents an experimental study regarding the machining of Calmax, a chromium - molybdenum - vanadium alloyed steel, with EDM. The control parameters are the pulse-on current, the pulse-on time and the open-circuit voltage, while the machining performance was estimated in terms of the Material Removal Rate (MRR), the Tool Wear Ratio (TWR) and the Arithmetic Average Roughness (Ra). The experiments were carried out based on Taguchi DOE and an L16 orthogonal array design. Finally, for the aforementioned performance indexes, Analysis Of Variance (ANOVA) was performed to determine how the machining parameters impact the process’ results.