Electrical energy is used to machine metals in electric discharge machining (EDM) process. EDM is a thermoelectric process, in which machining occurs without cutting force. Hence, electrical energy is converted to thermal energy to remove material. Usually, straight polarity is used in EDM, i.e., workpiece is connected to positive terminal (anode) and tool is connected to negative terminal (cathode). But, reverse can be possibly have rarely studied. An in-house designed table-top EDM was built to perform the experiments in straight and reverse polarity. Copper material was used as tool and workpiece to avoid the effect of different material. The voltage and polarity have significant effect on removal of material from workpiece. © 2021, Springer Nature Singapore Pte Ltd.