The anodic dissolution rates of two heat-resistant tungsten (12 wt %) and tungsten and rhenium (8 wt % W : 6 wt % Re) alloys in chloride, nitrate, and chloride–nitrate (30 g/l NaCl : 120 g/l NaNO3) electrolytes have been compared. An excess of the critical current density icrit depending on the hydrodynamic conditions leads to (i) the decreasing dependence of the current efficiency on the current density and (ii) the independence of the dissolution rate on the solution content. The mass-transfer mechanism, which determines the dissolution rate and the structure of superficial layers at i > icrit, is discussed. Data on the chemical content of the surface layers depending on the machining modes are presented. The modes of the electrochemical dimensional machining (ECDM) of the parts made of these alloys are offered to attain the best performance parameters for machining.