Mechanism of material removal after die-sinking electrical discharges machining, is quite complex. The principle is based on electrical discharge which occurs between workpiece and tool electrode. The electrical discharges always occur when complying the specific conditions, i.e. reaching the desired mutual distance (gap), mutual combination of main technological parameters and sufficient discharge energy. The size of discharge energy has a significant impact on the character of a crater in the workpiece and tool electrode. Desirable is only crater in the workpiece. The crater produced during one electric discharge in tool electrode is generally regarded as the negative site in die-sinking electrical discharges machining. The creation of this crater in the tool electrode has a direct effect on its wear. Paper aimed to describe the mechanism of material removal and its physical regularities of tool steel EN 90MnCrV8 (W.-Nr. 1.2842) in die-sinking electrical discharges machining.