A high-voltage direct current cut-off device, includes: a primary mechanical switch and a secondary mechanical switch placed successively between a primary point and a secondary point but either side of an intermediate point, a primary surge arrester arranged parallel with the primary switch, a secondary surge arrester arranged electrically parallel with the secondary switch. The secondary surge arrester is arranged electrically between the intermediate point and the secondary point, and in that the device comprises a capacitive buffer circuit electrically in parallel with the assembly formed by the primary switch and the secondary switch, and electrically in parallel with the assembly formed by the primary surge arrester and the secondary surge arrester, wherein the capacitive buffer circuit comprises an activation switch and a buffer capacitance.