Electro-Discharge Machining (EDM) is a suitable process used for machining very hard-to-cut materials. In EDM, the replica of electrode is obtained on the work piece by localized melting and vaporization of work piece material, but the electrode also tends to wear out to certain extent. In order to reduce the tool wear rate, the cryogenic treatment can be applied to the tool material. Cryogenic treatment is an ultra low temperature treatment technique which alters the properties of materials. In this paper, the effect of cryogenic treatment on a process parameter of EDM was studied. The Cryogenic treatment was applied to the copper electrode. Microstructure analysis was carried out using optical microscope. EDM experiment was conducted using untreated and cryogenic treated copper electrode and HSS tool steel as work piece material. Electrical resistivity was also measured. From the microstructure analysis, it was inferred that the grains of the cryogenic treated sample are finer than that of the untreated sample. Tool wear rate (TWR) was found to be reduced and Material removal rate (MRR) was improved due to the cryogenic treatment. This can be related to the reduction in electrical resistivity of cryogenic treated copper electrode.