This paper deals with the study of the influence of electrode material on the surface layer quality after EDM sinking. Graphite and Copper electrodes were used for EDM sinking of three materials from Tool Steel of Czech grade 19 096, 19 662 and 19 802. The surface layer quality of samples was analyzed for surface roughness, surface topography and residual stresses. The experimental results showed that the samples machined by Graphite electrode had a better surface layer quality than those machined by Copper electrode. All samples had lower values of roughness and thinner heat affected zone (HAZ) with Graphite electrode. Whereas, Copper electrode caused lower tensile residual surface stresses than Graphite electrode with roughing and finishing conditions specially for hard materials.