The article aims to show that the electrical discharge machining plasma can be developed in solid or gaseous medium, through the numerical and experimental evaluation of process performance. The plasma channel developed in gaseous medium is based on an electrical discharge developed in a gas bubble and the plasma channel developed in solid medium is based on underwater explosions. The main electrical difference between both mediums is on its electrical resistivity. However, if the radius of plasma channel increases, its electrical resistivity should decrease because its electrical resistance and applied current intensity are constant, or in other words, the applied electrical power is constant during discharge duration. Thus, the plasma channel is developed in gaseous and solid mediums, with same electrical resistivity and Joule factor, because the radius of plasma channel is considered constant during discharge duration. The comparison of numerical results of electrical discharge machining performance obtained through an electrical discharge machining plasma developed in gaseous and solid mediums shows high agreement with the experimental results. Therefore, the electrical discharge machining plasma developed in solid and gaseous mediums is reliable when hydrocarbon oil is used as a dielectric fluid due to the high degree of agreement of numerical and experimental results of electrical discharge machining performance.