[en] A numerical investigation shows the possibility of an electrothermal interelectrode breakdown of the wall of an MHD-channel. Two-dimensional calculations were done for conditions close to those in large-scale MHD channels: Reynolds number ≅5x10⁶, magnetic field 2.5 and 5 T, and average electron current density 0-5 A/cm². Examination of the charge at the anode wall, which consists of ceramic electrodes and insulators, shows that the most probable breakdown from an induced electric field occurs in the insulating gap from a continuous upward propagation of an overheated region of the insulator through the flow. Integral electrical characteristics of the discharge are presented for two values of the magnetic field and various electrical loads on the part of the wall under investigation, and the two-dimensional distributions of the potential, current, and temperature are displayed