Peculiarities of the cathode deposits forming along the length of the electrolyte pumping channel in impulse ECM of steels at the unipolar and the bipolar ECM have been discovered. It is ascertained that at the unipolar ECM four characteristic zones on the ET surface are formed. These zones are determined by a different combination of the current density and the hydrodynamic parameters of the electrolyte flow. A hypothesis is proved, that the cathode deposits are caused by electrophoretical transfer of positive sharged granules to the ET (electrode-tool) surface where they are adsorbed and adhesively connected with the cathode surface. A mechanism of the cathode deposits removal at the bipolar ECM has been revealed. It has been established that at the current inverse pulse apply an acidation (to pH = 1,2) of the anode-side area occurs, that is sufficient for chemical dissolving of the cathode deposits. Thus, an effective influence of the bipolar machining on a steel cathode has been ascertained. This influence results in chemical dissolving of hydroxide sheet in an acid medium, that provides the cathode being used repeatedly in a quantity automated production (without geometric, physical and chemical changes of the work surface). It has been showed that as the time of the unipolar machining increases the geometric dimensions and the phase composition of the cathode deposits are stabilized. At that the main volume of the deposits is formed during the first 15 minutes of processing.