[en] The authors use electrodes having an apparent surface area of 1 cm² and RuO₂ levels between 100 and 5 mole %, with a constant total amount of active mass of 1.7 x 10^-5 mole/cm² (17.2 to 0.86 g of metallic Ru per m²). The experiments were conducted in 4.27 M NaCl or NaClO₄ of pH ca 1.6 at 87 C. The method of gas-chromatographic determination of the oygen concentration in chlorine gas was used in combination with the polarization measurements. The polarization curves were corrected for the ohmic potential drops determined from oscillographic potential-decay curves which were recorded during brief current interruptions