The effects of pulse-on duration and finishing operation on the surface roughness and electrical resistivity of AISI D2 tool steel machined by the electrical discharge machining process are investigated. Experimental results indicate that surface roughness increased depending on the pulse-on duration. However, after the specific value, surface roughness is decreased. It can be seen that there are no notable effects of the pulse-on duration on the electrical resistivity, but the resistivity values are affected by the heat treatment and the finishing operation. Also, light microscopy and scanning electron microscopy have been used to study the characteristics of the surfaces.